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Volume XI, Number 29 

MEETING OF APRIL 25, 26, 27, 28, 1927 

"*- I 11^ 

Copyright, 1927, by 

Society of 

Motion Picture Engineers 

New York, N. Y. 



Engineering Societies Building 
29 West 39th St., New York, N. Y. 

Papers or abstracts may be reprinted if credit is given to the Society of 
Motion Picture Engineers. 

The Society is not responsible for the statements of its individual members. 


H. P. Gage 

L. C. Porter 


WiLLARD B. Cook 

Past President 
L. A. Jones 

Board of Governors 
W. B. Cook 
L. A. Jones 
W. C. Hubbard 
L. C. Porter 
F. H. Richardson 
J. C. Kroesen 
J. H. Theiss 
J. A. Ball 
J. I. Crabtree 

M. W. Palmer 

W. C. Hubbard 


A. M. Beatty 
Louis Cozzens 



Advertising and Publicity 
P. A. McGuire, Chairman 

George Edwards 
W. V. D. Kelley 

John H. Kurlander 
J. O. Kroesen 

Carl L. Gregory 
F. H. Richardson 

K. C. D. Hickman, Chairman 

John H. Theiss 
W. C. Vinten 

Herbert Griffith 
J. G. Jones 

Standards and Nomenclature 
Henry P. Gage, Chairman 
P. H. Richardson 

C. M. Williamson 
C. A. Ziebarth 

J. A. BaU 

J. I. Grabtree, Chairman 
C. E. Egeler 

L. A. Jones 

J. I. Crabtree 
R. P. Devault 
Carl L. Gregory 

C. E. Egeler, Chairman 

K. C. D. Hickman 
A. S. Howell 

W. V. D. Kelley 
John H. Kurlander 
Rowland Rogers 

J. I. Crabtree 

Pub lications 
E. J. Wall, Chairman 

K. C. D. Hickman 


April 1927 Report of the Progress Committee 


THOMAS A. EDISON, when quizzed on his eightieth birthday 
as to the future of motion pictures, repHed, "onward and 
upward." He struck the key note of the industr3\ One need not 
stretch the imagination far to paint a picture of the future in which 
sound synchronization, television, and stereoscopic principles are 
combined to give super-entertainment and service. Some day we may 
sit at home and see a great play, enacted in a magnificent theater in a 
distant city, projected in relief , and hear the words of the actors 
and the musical accompaniment. Instead of "tuning in" on our 
favorite musical entertainment, we may turn to our favorite play. 
Just what the future holds in store is a matter of conjecture, but it is 
certain that we are traveling "onward and upward." 

Perhaps the most recent e\ddence of progress which will affect 
our industry is the feat of sending action pictures by wire from Wash- 
ington to New York.^ Secretarj^ Hoover's face was transmitted and 
expressions were clearly shown as he talked over the telephone. 
And a studio entertainment was transmitted by radio from Whippany , 
New Jersey, to New York; scenes were thrown on the screen with, it 
is reported, all the reahsm of a motion picture. The voices of the 
actors were also carried by the radio. 

Fifty years ago wet plates and albuminized paper were the 
principle photographic materials,^ but after the introduction of the 
gelatin process the photographic industry expanded to the point 
where 40,000 persons are employed in connection with the manu- 
facture of sensitized materials and cameras. Though we were retarded 
at first by the complexity of the problem, much progress has been 
made in recent years, including improvements in sensitivity of emul- 
sions and applications of photography, aerial photography, photo- 
hthography, color sensitivity and motion pictures. 

There has been some contention recently as to just who "invent- 
ed" motion pictures.^ The developments of Jenkins, Friese-Greene, 
Lumiere, and Skladanowsky, have been debated with reference to 
their priority in the invention of the motion picture apparatus. In 
one history of cinematography recently written, it is claimed that 
L. Lumiere originated motion picture projection* and that Edison 

6 Transactions of S.M.P.E., July 1927 

perfected a means for viewing, photographically, motion synthesis 
which could be used by one person only at one time. (Lumiere's 
first motion picture films made in 1894-5, and which are in possession 
of W. Day, are still flexible and capable of projection.^) Another 
writer states that the motion picture business started in a small 
room on Broadway in 1895. Taking pictures out of the "peepboxes" 
and putting them on the screen was the task of the pioneers and is 
outlined in an article published early this year^ dealing with the 
evolution of the motion picture business. 

In the thousandth issue of Kinematographic Weekly Supple- 
ment, twenty years of film progress is summarized.'^ The early lantern 
inventions of Kircher, Brewster, down to those of Friese-Greene, 
Evans and Edison are reviewed. A 14-reel historical film entitled 
"Thirty Years of Motion Pictures" was one of the features of the 
Third Annual Films Convention of the National Board of Review.^ 
"The Motion Picture, its Broadening Influence and Uses" was the 
key note of the conference.^ The social influences of the motion pic- 
ture, its psychological influence, and its influence on the home and 
on the family were treated. 

The economic and social aspects of the motion picture have been 
studied by the American Academy of Political and Social Science.^" 
Among the many subjects treated are financing, production, art, 
music, lighting and application of the motion picture to education, 
business, science and entertainment. 

Many college men are taking up motion pictures as a career,^^ 
and actors are being sought from the colleges and universities.^^ 
Camera men were to tour universities throughout the country during 
April to make screen tests of undergraduates who appear as likely ma- 
terial for pictures. Every element that goes to the making of an actor 
of the highest type will be considered in the selection of the candidates. 
Facial features, physique, and intellect will undergo a thorough 

Respectfully submitted, 

Carl E. Egeler, C/la^Vma7^ 

A. S. Howell J. I. Crabtree 

Wm. V. p. Kelly R. P. De Vault 


' Rowland Rogers Kenneth Hickman 

Report of Progress Committee, 1926-1927 7 

Amateur Cinematography. 

Amateur motion pictures continue to take a prominent position in 
the industry. While their worth has been estabhshed in the fields of 
business and pleasure, new uses are constantly being discovered. 
Among the most recent applications is their use to correct the form of 
athletes. ^^ 

Much has been written on the precautions to be taken with ama- 
teur apparatus and many suggestions have been given. Suitable ar- 
rangement of the room during projection and the proper care of the 
projector during its use have been discussed/^ as has the proper 
length of shots for average scenes taken with 16 mm cameras. ^^ A 
table was included^^ showing the relation between crank turns, pic- 
ture frames and footages for 16 and 35 mm film; the 10-second scene 
is advocated. 

A new film library has been opened making possible the purchase 
of professional subjects on 16 mm film in short lengths at a nominal 
price ;^^ the subjects are reductions made from standard 35 mm pro- 
fessional films. 

While the 16 mm size film is undoubtedly cheaper, great econo- 
mies in the use of 35 mm film may be obtained, it is claimed, by using 
short pieces and end runs.^^ Printing by the reversal process cannot 
be carried out, but the negative may be developed by the amateur 
and sent to a laboratory for printing. 


One of the innovations at the Motion Picture Trade Exposition 
held March 7th to 12th, 1927, at the Ambassador Auditorium, was a 
vest pocket moving picture camera that, it is asserted, will faithfully 
photograph any scene which can be reported on regulation sized 
films. ^^ The camera weighs 14 ounces and is only 4 inches in length. 
Its magazine holds 20 feet of extra thin film stock of standard size. 

A new speed motion picture camera has been designed and demon- 
strated which is capable of taking 2,600 photographs a second, more 
than 150 times as many as the ordinary motion picture camera. ^^ 
It is used to photograph electric spark discharges and for other 
experimental purposes. 

The United States Army has developed a new aeroplane motion 
picture camera which takes a continuous series of pictures, records the 
time tney are taken, the angle of the camera to the ground, the alti- 
tude, the number of exposures, the focal length of the lens, the day. 

8 Transactions of S.M.P.E., July 1927 

month, year and other particulars. ^o The camera does not require an 
operator and hence may be placed in the fastest single pursuit planes. 
The pilot merely starts the camera when he is over an area which he 
wishes to record and it takes the pictures and all the necessary data; 
an area of 180 square miles at an altitude of 15,000feet can be mapped 
out allowing for 50 per cent overlap on the films. 

Colored Motion Pictures. 

While there continues to be no outstanding developments in the 
application of color cinematography, there is considerable patent 
activity in this field. 

A new process of photography and cine-photography in color has 
been devised^^ in which an ordinary contact positive is printed from a 
single negative exposed through a grating with rulings parallel to 
tricolored filter bands in the objective. The positive is viewed directly 
through a sheet of ground glass, or by projection, being illuminated 
by a system of band filters and a grating similar to that in the camera. 
In cinephotography the grating is printed photographically on one 
side of the film before the panchromatic positive emulsion is coated 
on the other side. 

Another motion picture color process has been developed which 
is said to have a combination of additive and subtractive features.^^ 
Two images are taken, one recording red, yellow, and blue-violet, 
and the other orange, yellow, green, and blue. The corresponding 
positive images are colored yellow and are projected alternately 
through screens of violet and blue-green. 

In projecting colored pictures, instead of using color filters which 
absorb part of the light, a series of prisms have been arranged in 
echelon, dispersing the light into its several color components, thus 
utilizing practically all of the light. -^ 

A patent has been granted on a process of producing motion 
picture film having identical emulsion quality. Tw^o films which were 
originally cut from adjacent areas of a wide film band are exposed back 
to back, 24 and complemental pictures are printed on the registering 
areas; these are then developed by a relief method. 

A motion picture film for use in the Keller-Dorian color process 
has been developed in which the bases of the lenticular elements are 
hexagonal and fit closely together. ^^ The film used in taking is thicker 
than normal and the number of elements to the millim_eter is less than 
26; in projecting the number is greater than 23, the film is of normal 

Report of Progress Committee, 1926-1927 9 

thickness and the emulsion is of very fine grain. A supplemental 
collimating lens, such that the pupil of emergence of the main 
objective, as viewed from the film, is situated at infinity, or at least a 
great distance in front of the lens, has been designed for use with the 
Keller-Dorian process ;2^ and a method has been devised for making 
cylinders which impress reticulations into film to be used in this 


Much interest and activity are being displayed in the educational 
application of motion pictures. The worth of motion pictures in the 
schools and for other educational purposes is not yet generally estab- 
Kshed but many experiments have been and are being made from 
which conclusive evidence may be drawn. Perhaps the largest and 
most important of these is now being launched in many public 
schools.^ ^ Actual work is being done upon a series of fifty motion 
picture films especially designed for use in the class room. These are 
intended for fourth and higher grades in selected schools and will be 
shown within a two-year period assigned for the experiment. The 
films are laid out with a definite idea of following certain prescribed 
teachings. Each picture is being assembled by scientists and peda- 
gogues with the realization that to be instructive the picture m.ust also 
be interesting. If expectations are realized the films may be generally 
adopted for class room work. 

Visual education by motion pictures and lantern slides has been 
tried out in the Potter's School of Pawtucket, Rhode Island.^^ There 
it is concluded that this method of teaching saves time, clarifies and 
clinches half -formed text-book impressions, and vitalizes dull sub- 

The motion picture program for a high school has been studied 
with reference to the types of pictures desired by each department of 
the school and methods of avoiding conflicts and repetition in classes.^" 
A survey has been made of the relative status of fourteen different 
visual aids used in intermediate schools in various cities throughout 
the United States.^^ Films are considered very effective whenever 
motion is to be shown, but it is said that they have certain weaknesses. 
A nationally known educator has conducted experimental tests upon 
films made for class room use, and reported his findings. ^^ 

The educational application of motion pictures has also been tried 
out in England. It is asserted, in a report from the County High 

10 Transactions of S.M.P.E., July 1927 

School for Boys at Altrincham,^^ that no modern school without the 
cinema is properly equipped for the business of teaching. A discussion 
of the supply of films, the cost, and of the tests and results obtained, 
is given in the report. 

Russia also seems to be using the motion picture for this purpose 
as evidenced bj^ a recent order from the Optical Trust of Lenin- 
grad, Russia, calling for 2,000 projection machines^^ which are to be 
used in public schools for visual education. 

It is said that teaching by talking and motion pictures should not 
be attempted at the same time. ^° The teacher should first talk, next 
project, and then summarize both the talk and the picture. The 
films should be correct to scale, artistic, worth while, true to life, of 
immediate appeal, should promote favorable emotional reactions and 
should provide stimulation to correct responses. ^^ 

While most of the research work and experimenting is being done 
in connection with the lower grades, some colleges and institutions of 
higher learning recognize the possibilities of motion pictures. The 
Bellevue Hospital Medical College is now using them almost entirel}^ 
in place of the amphitheater as a means of demonstrating operations 
to post graduate students.^'' The films are also being used to show the 
progress and cure of a disease and to bring microscopic studies close 
to the students. 

Paralleling the activity in using motion pictures as an accessory 
to teaching is that of educating people in the art and science of motion 
picture photography. Several leading colleges and universities are 
either planning or have established courses in this subject . Lectures on 
motion picture topics will be given in the course in Business Policy at 
Harvard L^niversity.^^ xAinong leaders in the motion picture industry 
who are scheduled to talk are Cecil De Mille and Milton Sills. Plans 
are also being discussed for courses in IMotion Picture Photography, 
Motion Picture Architecture, Business Administration and Scenario 
Writing which may be offered at Columbia University. ^^ 

The army signal school at Post Monmouth, New Jersey, is to give 
a course in motion picture photographj^^^ which will train students in 
the making of historical and news pictures, thus better enabling the 
army to preserve pictorial records of its present and future activities. 

Some foreign activity has also been evidenced in this field. A 
school has been established in Paris^^ to teach photography and 
cinematograph}^ to technicians. 

Report of Progress Committee, 1926-1927 11 

Films and Emulsions. 

The most prominent progressive step in connection with films and 
emulsions is the increasing use of panchromatic motion picture film. 
It is said that more panchromatic negative film is now used than regu- 
lar film>2 XJntil recently panchromatic materials were used only for 
the three-color process, but recent improvements in keeping quality, 
speed, and ease of handling with the aid of desensitizers, have made 
panchromatic materials desirable for motion picture, portraiture, and 
landscape photography. Its application to motion picture filming has 
made unnecessary the use of any other than ordinary "make-up," 
and permits lighting of studio sets in a manner similar to real life.^^ 

Lighting problems of desert scenes in filming "The Winning of 
Barbara Worth" were said to be greatly simplified by the use of 
panchromatic film.^^ 

To give a complete understanding of the principles involved in 
obtaining any desired reproduction of tone values by the photographic 
process, a thorough discussion of many factors, including the nature 
of light and radiation, the sensitivity of the eye and of the photo- 
graphic materials to radiations of different wave lengths, the quality 
of radiation emitted by various light sources used for illuminating 
the set, and the reflection characteristics of objects, are covered in a 
series of articles being written on the subject "Panchromatic Motion 
Picture Film Negatives."*^ 

Paralleling the adoption of panchromatic emulsions is the 
activity toward increasing the sensitivity of all emulsions. Consider- 
able work is evidenced at the present time in the direction of finding 
baths for treating negative film before exposure to increase its speed 
to an abnormal amount. ^^ 

The sensitiveness of a silver emulsion is extended by including 
salts that are soluble in water,^^ the anions of which contain at least 
3 atoms of an element of the sulphur group, and the sensitivity of 
silver salt emulsions has been increased^^ by the addition of thiazol 

A new method of improving the light sensitiveness of photo- 
graphic material which involves a colorless organic sensitizing material 
preferably derived from animal tissue in concentrated form, has been 
patented ;^^ and a patent has been issued on a gelatino-silver-halide 
emulsion,5o made by including a sensitizing material extracted from 
seed tissue. 

12 Transactions of 8.M.P.E., July 1927 

A photographic emulsion has been produced, based on the use of 
salts of mercury, which functions as a developing out emulsion. ^^ 
Its light sensitiveness is increased by the addition of an independent 

Autochrome plates may be hypersensitized^^ by bathing with a 
solution of panto chrome containing a minimum quantity of ammonia- 
cal silver nitrate. Other sensitizing dyes may be substitued for 
pantachrome. Fast non-color sensitive materials can be made ortho- 
chromatic by the use of the same dye. 

Further study has been made of the reciprocal relation between 
time and intensity in photographic exposure. ^^ It has been found that 
the maximum density obtainable with complete development depends 
upon the intensity used in making the exposure. Thus for silver 
halide grains there is an intensity-threshold below which the films 
cannot be developed no matter how long the exposure time is pro- 
longed. Conversely, if the exposure intensity be sufficiently high all 
of the silver halide present in the emulsion can be developed. The 
causes of photographic sensitivity have also been explained. ^^ 

While the problem of increasing the sensitivity of emulsions seems 
to be receiving most attention, other discoveries or innovations are 
being made, all of which tend to improve the final product. An acid 
amidol developer has been devised^^ which contains chrome alum; 
it prevents fog and makes possible the development of good negatives 
from bad over exposures. 

A method representing a great advance in the measurement of the 
iodide content of photographic emulsions has been developed^^ 
and will be used by all large manufacturers to control the quality of 
their emulsions. It is a potentiometric method in which silver 
halide is dissolved in an excess of potassium cyanide, granulated zinc 
added and the solution boiled to reduce the silver halide to metallic 
silver. Acetic acid is added in excess and the solution is again boiled 
to remove all the cyanide. Ammonium nitrate is put in and the 
solution is then titrated with a silver nitrate solution and the end 
points are determined electrometrically. As little as 1 per cent silver 
iodide can be estimated with considerably accuracy in mixtures of 
silver halides by this method. 

Direct positives have been made by the use of copper chloride, ^^ 
a reversed positive being first produced on bromide paper by bleaching 
.the strongly developed negative image with copper chloride. The 

Eeport of Progress Committee, 1926-1927 13 

resulting silver chloride is then dissolved in ammonia after being 
washed, and the remaining silver bromide is developed in strong light 
to a positive image. 

A series of experiments have been performed in study of the 
relation between the absorption of the various sensitizing dye-stuffs 
and the reversing of the red and infra-red rays.^^ It was found that 
dye stuffs which have a strong absorption band in the region of wave- 
lengths longer than 550^t are effective in obtaining the reversed im- 

A micro colorimetric method of silver analysis,^^ which involves 
precipitation of silver as colloidal silver-siilfide, permitting silver on an 
area of one square centimeter of density 0.10 to be determined to a few 
per cent, has been worked out. Several methods of recovering silver 
from fixing baths have been analyzed^" with respect to the properties 
of the de-silvered hypo and possible financial returns. 

The making of good duplicate negatives calls for great skill and 
makes stringent demands upon the materials available. ^^ An expo- 
sition of the requirements and of the process involved was given in a 
paper presented before the last meeting of the Society. It is necessary 
to choose an emulsion^^ having considerable latitude and it should be 
developable to a low gamma. 

A motion picture film has been made having a plurality of small 
protuberances along the film edge which, ^^ it is claimed, increase the 
durability and lessen abrasion marks. The optics of production of rain 
effect from scratches and scars on the support side of positive film 
have been explained^^ and various methods of diminishing this effect 
and prolonging the useful life of old films described. 

A new film cement consisting of collodion, acetic ether, alcohol, 
amyl acetate, ether and acetone has been patented. ^^ 

A film is said to have been perfected by a British inventer which 
cannot burn,^^ and which supposedly may be produced on a commer- 
cial basis. 


The experimental work of motion picture photography has long 
been an expensive item in connection with production costs. There 
has been much duplication of effort by cinematographers in various 
studios. With the purpose of remedying this situation, a research 
laboratory has been established by the American Society of Cinema- 
tographers in Hollywood,^^ to make authentic tests on standard 
cinematographic subjects, 

14 Transactions of S.M.P.E., July 1927 

The question as to whether Roentgen cinematography can become 
a current method of research has been considered. ^^ A new indirect 
method has been suggested which consists in placing a screen of 
selenium cells in the path of the X-rays, with each cell in an individual 
circuit and connected to a lamp. A curtain made up of such lamps will 
give a picture which can be photographed. 

For some time the Cleveland Public Library has cooperated with 
exhibitors, advance publicity men and the distributing offices in New 
York City in maintaining a film library. *^^ The method of cooperation 
is so arranged that lists of films coming for a year ahead are on file in 
the Order Department of the library, and in the various book divisions 
likely to be affected by them, months before the making of the film 
has begun, enabling the library to list book connections and purchase 
in season the books needed to supply the demand created by this 
library-film cooperation. It makes possible the careful reading of 
books and plays to be filmed, to discover all the book connections. 

Illuminants and Lighting Effects. 

The adoption of panchromatic film is leading to the increasing 
use of incandescent lamps in studio fighting. The incandescent light 
source emits light of all colors, but is strong in reds and yellows, and 
is therefore especially adapted to use with panchromatic film. The 
elimination of so-called "Klieg Eyes," attributed to exposure to light 
from carbon arc lamps, is reported^" by a large producing organization 
which employs incandescent lamps and panchromatic film. 

A study has been made in Fra;nce of the properilluminants to use 
in the cinematographic studio. '^^ The use of the blue and ultra-violet 
arc was found to be injurious to the actors, and screening out the 
ultra-violet reduced the photographic efficiency to an impracticable 
value. A flame arc emitting a greater proportion of visible radiation, 
or gas-filled tungsten lamps operated over voltage, and used in 
conjunction with orthochromatic or panchromatic film, are preferred. 
The use of panchromatic film and one of these light sources eliminates 
the complications of ''make-up" and choice of colors in scenery. 

A new high intensity projector arc lamp has been introduced^^ 
which is designed for very high amperages. It has a new feed assembly 
and greater forward adjustment. A combination high intensity flood 
lamp and single effect projector has been developed which is adapted 
to extremely long projection distances. ^^aj^ consists of a high intensity 
arc lamp and a single optical system provided with projection lenses 

Report of Progress Committee, 1926-1927 15 

of different focal lengths, effect holders, etc., all easily swung into 
place. A French invention in arc lamps for projectors utilizes a single 
carbon which is of small diameter and lies horizontally, feeding to- 
ward the condensing lens.'^^ The negative electrode is a metallic ring, 
and the arc is formed between this ring and the carbon. The light is 
said to be extremely brilliant, steady, and cooler than the usual arc. 
It is also claimed that with equal screen brightness a current economy 
of 50 per cent is obtained. 

A three-carbon arc has been developed ^^ in which one of the car- 
bons is placed just above the positive crater. After the positive carbon 
burns away, the flame touches the third electrode, causing a magnet to 
be energized and to feed the positive carbon forward. The flame then 
ceases to act on the third electrode. 

One author, in describing a new condensing lens system, erron- 
eously states that with mirror arcs, 60 per cent of the total light flux 
may be projected to the screen ;^^ a figure of less than 10 per cent 
would be more nearly correct. He states further that with typical 
condensing systems only about 3 per cent of the light reaches the 
screen. The Bausch and Lomb relay system is then described, and it 
is stated that while it collects less light than does a mirror, it utilizes 
more efficiently that which it collects. A patent has been granted 
on an optical system consisting of a reflector and special condensing 
lenses, one having a small negative lens inserted at its center. ^^ 

A discussion has been published^^ of special lighting effects used 
in taking night scenes, with special reference to the relation between 
the amount of general and local lighting. 

Laboratory Equipment and Apparatus. 

Three methods used in printing motion pictures are the step-by- 
step, the continuous, and the optical whereby a lens is employed to 
carry the image of the negative to the positive. In a paper presented 
before the last meeting of the Society, a daylight optical printer for 
the reduction of standard size negatives to 16 mm positives was des- 
cribed.^^ In another paper presented at this meeting, a description 
was given of four different motion picture printing machines, and of 
their operation. '^^ 

There is a new process for film regenerating consisting of an 
apparatus divided into three compartments ;^° the film is first cleaned 
by brushes, then passes into the second compartment where it is 
exposed to the vapor of a mixture of acetone, acetic ester and such 

16 Transactions of S.M.P.E., July 1927 

softening agents as camphor, phthalic acid ester, nitrobenzol, etc. 
In the last compartment the film is polished. All scratches and 
abrasions are removed by this process. 

An illuminated box has been designed for the direct inspection of 
motion picture film.^^ The lamp housing is at one side of an inclined 
film gate and a prism reflects the image of the film to an observing 

A pneumatically controlled machine has been developed^^ 
to test motion picture films for slits, breaks and holes. A selenium 
cell and an electrical circuit has been used as a means of measuring, 
by light passed through motion picture film, the density of the film 
for printing. ^^ 


Lenses are being designed to work at faster speeds. The F/1.6 
objective lens is now quite common. ^^ Tables have been compiled 
showing the depth of definition for 35 mm, 42 mm, 50 mm and 75 mm 
objectives at apertures from F/2 to F/9 inclusive. A lens manu- 
facturer has applied for a patent on a lens with an anastigmatically 
flattened field freed from coma and flare, and working at the large 
aperture of F/1.4.^^ 

A study has been made of the relative characteristics of a motion 
picture positive and its screen image with reference to the effect of 
projection lens flare upon the contrast of a motion picture image. ^® 
It has been concluded that the veiling brightness due to flare is 
directly proportional to the average transmission of the projected 
positive; that the flare-forming characteristics of a lens may be 
expressed as the ratio of the flare brightness to the average brightness 
of the picture; that the effect of flare upon the characteristics of the 
picture can be computed from a knowledge of certain characteristics 
of the positive; and that the effect of lens flare on quality of tone 
reproduction is to warp the shape of the reproduction curve and de- 
press the contrast. 

New Amplications. 

The possible applications of motion pictures are without number. 
New uses are continually being found, most interesting of which are 
those that serve to promote the general welfare of human beings. At 
the Montreal convention of surgeons, Mr. Will Hays outlined the 
advantages of motion pictures in helping phj^sicians teach the value 
of health and the importance of proper living. ^^ He also pointed out 

Report of Progress Committee, 1926-1927 . 17 

that the use of motion picture will preserve for future generations the 
technique and operative. skill of eminent surgeons of the d^y, bringing 
the work of these masters to students in every part of the world. 
Physicians are planning to use motion pictures in conducting a 
bacteria war.^^ Films of bacteria and animalcules are claimed as 
made possible by a recent development for separating the heat waves 
from the Hght . 

The practical difficulties encountered in the taking of wildbird 
and wild animal motion-pictures, and the solution of these difficulties^^ 
was the subject of a paper on the use of the telephoto lens presented 
before the Society. 

Motion photomicrography has been left largely to a few special- 
ists because of technical difficulties about which little has been writ- 
ten. However, with a Httle serious application, the principles involved 
may be readily grasped. An extensive paper was presented^° at the 
last meeting of the Society upon the theory involved and its applica- 
tion to specific samples. 

Exposure factors for forest photography have been approximately 
determined. ^^ Though it is impossible to give exact tables, experience 
has shown that they are as follows: landscape in the open, factor of 1 ; 
leafless woods, factors of 5; leafy hardwood stands, open pine stands, 
factor of 25; open hemlock stands, factor of 75; open pine stands, 
dense fohage, 200; dense pine stands, dense foliage, 1000. 

A specially constructed twenty-ton motion picture camera was 

used to film Saturn and his rings from the Yerkes observatory on 
January 28. S2 

Immigrants may now have some knowledge of the ideals of the 
United States before they set foot on American soil, through the use of 
films displayed on ship board. ^^ A large commercial line has inaugur- 
ated an Americanization program of films for aliens on one of its 


The question as to whether or not motion pictures are harmful to 
the eyes has been discussed by a Philadelphia doctor^"^ who contends 
that there can be no sweeping answer in the affirmative or in the 
negative. He says that while for a few the movies area positive men- 
ace and for many they are a source of discomfort and annoyance, for- 
tunately for the majority of people they are not harmful, as has been 
alleged, though not particularly beneficial to the eyes. He discusses 

18 Transactions of S.M.P.E., July 1927 

the factors which may cause annoyance and discomfort and suggests 
possible remedies or helps. In general it appears that pictures in 
natural color are much less conducive to eye strain than those in 
black and white. Among the questions which have been studied®^ 
are ''memory color" phenomena, depth effects, and hygienic aspects. 
The action of the heart has been studied with the Rontgen 
Cineomatograph.^^ Full size 8"X10" radiographs of the heart were 
made serially at a rate of 15 per second. 


The usual number of patents are being issued on various 
devices for the improvement of projection and the problem of con- 
tinuous projectors is still in the good graces of inventors. The high 
intensity of illumination at the aperture, the noise of operation, and 
the rapid wear and tear of films with the intermittent motion picture 
projector have caused many attempts to utilize a continuous motion 
of the film. Practically all of the devices proposed or developed to the 
present time have been much more ingenious than practical. A 
continuous projection apparatus and camera have been developed^^ 
which are based upon the fact that if two mirrors are arranged as in a 
single periscope and if the exit mirror be given a proper rotation 
around an axis perpendicular to the axis of the tube, the motion of a 
point in the image can be compensated. 

At an exposition of photography and cinematography held in 
Berlin recently, an amateur motion picture camera was shown which 
had a time release controlling the spring drive, permitting the opera- 
tor to appear in the picture. ^^ A motion picture projector having 
automatic lubrication, and feed roll friction controlled by the weight 
of the film roll; and a Mechau projector which operates as slowly as 
two frames per second without flicker were also demonstrated. 

A Frenchman has developed a tiny moving picture projector 
which is no bigger than a cigarette case^^ and which, it is reported, 
can project pictures as large and clear as ordinary ones! 

A leading model standard projector has been improved^"" by the 
incorporation of mechanical in place of electrical speed control, a 
miniature framing lamp, an automatic loop setter, and an improved 
stand. A projector has been designed having a governor which 
controls the number of filaments lighted in a special lamp and also 
the speed of the film movement.^°^ 

Report of Progress Committee, 1926-1927 19 

Another shutter has been devised which, it is claimed, produces 
flickerless pictures. ^^^ The shutter blade has a transparent rippled 
surface and is preferably used with a supplementary light so that 
some illumination may be directed to the screen while the film is mov- 

Patent activity in the field of safety shutters has turned from the 
use of air blasts at the film gate to the use of various safety shutters 
and other fire preventatives.^"^ A device for reducing the light when a 
motion picture projector is stopped to project stills has been de- 
signed. ^°^ A notch in the film engages a movable projection which con- 
trols a switch that throws resistance into the lamp circuit. It is also 
operated when the speed of the mechanism is reduced. In another 
safety device a film roller breaks the motor circuit when the film 
breaks or fails to run through the machine, ^°^ and a film magazine has 
been devised which has a small drum of noninflamable gas connected^ 

Fires should be locahzed in the projector itself and not in the 
projection room, and it is said that British legislation may make fire 
traps compulsory on projectors. ^°^ 

A new safety device which renders impossible a fire in the pro- 
jector is said to be perfected. ^°^ It has nine control stations at the 
various sprocket wheels and belts, and an electrical system whereby 
a break in the film, buckling, blowing of the fuse, etc., will instantly 
throw a lamp house dowser. Should the system fail to work, the 
mechanical features of the invention function and the failure of the 
film to properly pursue its course instantly shuts off the power and 
throws the dowser. 

In projection it is often important to get as much light as possible 
through the film aperture, but it is also necessary to consider the tem- 
perature of the film surface at this point. With the introduction of the 
mirror optical systems, in which the heat at the aperture is very much 
more than in the case of lens systems, this necessity has come more 
into prominence, and the relation between the temperature at the 
film and the useful Hght flux has been given new study .^°^ It was found 
that the temperature in the case of a metal mirror was almost twice as 
great for a screen illumination of fixed value as that produced by a 
system employing a glass mirror and condenser. This ratio was 
somewhat less for a screen illumination of double this value. A 
theoretical loss of 28.6 per cent of available flux was measured in a 
condenser system composed of a glass parabolic mirror and a con- 

20 Transactions of 8.M.P.E., July 1927 

denser of 50 cm focus and 20 cm in diameter, which was due to 
absorption and dispersion. The effect of the brightness of the Hght 
source and of the coohng mechanism was also included in this study. 
Comparative temperature measurements in the aperture of 
motion picture projector gates have been made from measurements of 
the resistance of a blackened wire in the gate/^° and Odencrants' 
experiments on the temperature in film gates have been summarized. ^^^ 
An opaque black body placed in the gate is the standard receptor. 
Film during normal travel through this region should not reach a 
temperature of 90° C though its inflammation point is about 155° C. 


A very complete analysis of the reflection characteristics of many 
commercial projection screens was presented"^ at the last meeting of 
the Society. Tables were included which may be applied to particular 
problems in selecting the proper types of screens for auditoriums and 

A semi-specular screen has been made from paint, aluminum and 
gilt spangles and used in some large London theaters. ^^^ This screen 
is found to give a strong axial reflection without rendering the picture 
dull to patrons in the front and side seats. 

A paint has been devised for motion picture screens^^^ which con- 
tains small amounts of color. These, it is claimed, do not visibly alter 
the whiteness of the screen coating but are "responsive" to color in 
the projected beam. 

More perfect reproduction is said to result through the use of a 
projection screen including a transparent plate having fine sinusoidal 
corrugations formed onits display side and covered with a semi- opaque 
varnish layer.^^^ 

A translucent screen has been devised for daylight projection"^ 
which has one face polished and the other, which faces the spectators, 
matte and dark. Dark coverings have been arranged both behind and 
in the front of a translucent screen to permit the passage of projected 
light and to obstruct dispersed light. ""^ The front covering may be a 
black net having its vertical threads more widely separated than the 
horizontal ones. 


^Exports of motion picture films during 1926 were somewhat less 
than during 1925 ;"» 214,026,620 Unear feet of positive film valued at 

Report of Progress Committee, 1926-1927 21 

$6,395,923 were exported during 1926 as compared with 225,656,151 
linear feet values at $6,787,687 exported in 1925. Negative film 
exports in 1926 amount to 6,600,000 linear feet valued at $1,334,960 
compared with 9,929,643 linear feet, valued at $1,893,058 exported in 
1925. Latin America during 1926 led the foreign market for Ameri- 
can films from the standpoint of quantity, however, Europe led from 
the standpoint of value. Australia was the largest individual market 
for our films in 1926, with Canada as second largest and Argentina 
third. From these figures the negative film was valued at 2.02 per 
linear foot and positive film 2.98 per linear foot. 

Twenty thousand miles of film were used during the year 1926 
by amateur motion picture makers. ^^^ It is predicted that consider- 
ably more will be used in 1927 . 

A two-year survey conducted by a current magazine indicates 
that there were 14,991 motion picture theaters in the United States 
in the year 1926. ^2° This is an increase of 306 theaters over 1925. 
There are 2,000 first run theaters. 

According to figures compiled by the Census Bureau, motion 
pictures produced in the United States in 1925 cost almost 
$100,000,000.^2^ This figure is considerably higher than that compiled 
in 1923 when the first census was taken. It was reported that there 
were 5,945 salaried officers and employees of the industry in 1925. 
The salaries for the year totaled $35,950,778. 

The total seating capacity of motion picture theaters in this 
country has been said to be 18,500,000 or one seat for every six 
persons. ^22 ^ large seat corporation reported sales for the year in 
excess of $10,000,000,123 

During the past year twenty companies have been organized for 
the purpose of producing motion pictures in China. ^^4 xhere are at 
present approximately fifty companies producing pictures there, not 
more than 10 per cent of which are on a paying basis. It is reported 
that there are about 106 theaters with a total seating capacity of 
approximately 68,000. Motion pictures are also shown to a certain 
extent in educational institutions and lecture halls. 

A motion picture film producing organization has been formed in 
Burmai25 ^^^^ jg composed entirely of natives. The studio, which is in a 
secluded part of the Burmese jungle, is entirely up-to-date. They have 
already produced eight pictures deahng with Burmese fife which 
attract Europeans as well as natives to the theaters. 

22 Transactions of 8.M.P.E., July 1927 

The United States Navy is said to be the largest motion picture 
distributor in the world. ^^^ Simultaneously with the release of features 
to the large theaters, the navy starts two prints on circuits on which 
the films travel three years before returning to storage, the reels 
going from ship to ship until every vessel of the fleet has had its turn, 
then, after overhauling they go the rounds of the naval stations. 
Motion pictures are also used as an added inducement to join the 

Stereoscopic Projection. 

It is rather difficult to determine just what actual progressive 
development has been accomplished recently in plastic cinematogra- 
phy. Reports of perfected apparatus to produce this effect are widely 
distributed, and it is certain that there is much interest in this field. 
An analysis of the principles involved in stereoscopic and pseudo- 
scopic projection, and a resume of various means and methods which 
have been tried and patented, were given in a paper presented before 
the last meeting of the Society. ^^7 

It has recently been claimed that actual third dimension pictures 
showing length, width and depth on the screen are an accomplished 
fact, and that photoplays made by a new process will be available for 
all theaters regardless of size or equipment without making any 
changes in the theater whatever. ^^^ 

A new binocular stereoscopic camera has been developed and is 
regarded by its inventor as one that portrays pictures in the true three 
dimensions. ^2^ When pictures taken with this camera are viewed 
through a special appliance, the screen seems to disappear and there is 
no consciousness of a picture having two dimensions, exposed on a 
flat surface. The success of the camera is said to be explained by the 
theory of binocular vision. 

A patent has been granted on a motion picture apparatus for 
producing pronounced relief effects by giving the taking apparatus a 
constant to and fro motion along a straight line and causing it to move 
from left to right, front to rear, and top to bottom, i^° and another 
patent has been issued on an apparatus which obtains an effect of 
relief by taking alternate pictures under different fightings. ^^^ The 
motion picture camera is connected to a light control that causes the 
lightings to alternate in synchronism with the exposures. 

Talking Motion Pictures. 
The talking film is at the present time popular because of its 
novelty but it will undoubtedly be used extensively in the future to 

Report of Progress Committee, 1926-1927 23 

replace orchestra and vaudeville parts even if the talking play does not 
become popular. ^^^ While early motion pictures were shown without 
music and technical and travel pictures of today are still impressive in 
silence, the modern audience requires music synchronized emotionally 
with the subject matter, with a background of perfect silence .^^^ 
A survey of the present progress in the art of "Talking Pictures" 
has been published in a European magazine. ^^"^ 

A new device for furnishing incidental music for the picture, 
called the *'Remaphone," has been developed. ^^^ It consists of a 
Victor "Electrola" with two turning tables connected by a shaft to the 
two projection machines in the booth. Perfect synchronization of 
picture and music is said to be obtained. Another apparatus, called 
the "Photophone," has been perfected. It is a combination of a 
motion picture projector and the pallophotophone.^^^ The pallophoto- 
phone makes a photographic print by means of a vibrating beam of 
light on a strip of film, and when the film is run through the reproduc- 
ing machine the vibrating beam of light retranslates the photographic 
sound record into audibility and is amplified by a loud speaker to any 
degree desired. 

A new mechanism made under the Vitaphone patents carries the 
sound waves on the film,^^^ thus making it impossible for the sound to 
become out of synchronization with the action of the picture. "Movie- 
tone" pictures is the trade name given the device, which is operated 
with the Vitaphone mechanism. 

Instructions for the operation and maintenance of the Vitaphone 
synchronous reproducing system have been published^^^ for the 
benefit of the projectionist. A motor switch, a volume indicator, two 
amplifiers, an equalizer for improving quality of reproduction, and a 
general power supply panel are essential to start the film and sound 
record in synchronism. Either alternating or direct current may be 

It is claimed that the tone of the sound reproduced from a photo- 
graphic film record may be improved by reproducing the sounds at 
least twice in such a manner that they reach the ear with a phase 
difference corresponding to a time interval of 1/8-1/30 of a second. ^^^ 

Some effort has been directed among producers toward standard- 
ization of sound reproducing devices. ^*° The adoption of different 
systems by each producer is said to restrict competition since pro- 
ducers will eventually be hmited in their business to those theaters 
using their own system, and the theaters will be hmited to deahng 

24 Transactions of S.M.P.E., July 1927 

with producers having the system corresponding to their own par- 
ticular device. 

An experiment was recently made in Germany in which film and 
radio were synchronized for the transmission of a scientific medical 
lecture to a motion picture audience. ^^^ The transmitter and the 
projector at the sending station were connected with a synchrono- 
meter, and the same arrangement was carried out in the theater, 
thus causing both motors to run at exactly the same speed. 


Paralleling the efforts made toward perfection or improvement of 
talking and stereoscopic pictures is the continued activity toward the 
development of a practical device to transmit still and motion pic- 
tures by wire and by radio. It is predicted that within the next ten 
years, we may sit at home and see motion pictures flashed on a screen 
through use of the radio. ^"^^ 

A method is being developed which, it is reported, will accomplish 
instantaneous transmission of pictures. ^^^ The transmitter employs a 
Kunz photo-electric cell and a four-electrode amplifying tube. The 
receiver uses a Braun tube, which automatically insures synchronism. 
Twenty pictures are sent per second which insures continuity of 

Infra-red rays have been used recently in London to transmit the 
images of the faces of people sitting in a dark room to a screen fixed 
in another room, also dark.^^^ The inventor of this apparatus believes 
that in another year it will be a commercial proposition, retailing for 
S150.00. It will enable users to see and hear at the same time when 
used in connection with either the telephone or wireless. 

1 Chicago Tribune, Apr. 8, 1927. 

2 C. E. K. Mees, Ind. Eng. Chem. 1926, 18, 915. 

3 W. Day, A. Pereira and S. Read, Phot. J. 1926, 66, 359. 

4 M. Coissac, Gauthier-Villars, Paris, 1925. 
\Kine. Weekly, 1926, 115, 89. 

« C. E. Hastings, M. P. World, 1927, Jan. 1, 18. 
' T. Brown, Kme. Weekly Supp. 1926, i^^, 93. 

8 M. P. World, 1927, Jan. 29, 332. 

9 M. P. News, 1927, Jan. 14, 136. 

10 Ann. Amer. Acad. Polit. Soc. Sci. 1926, 128, Nov. 

11 M. P. World, 1927, Mar. 19, 189. 
. 1^ M. P. News, 1927, Mar. 12, 869. 

" K. A. Barleben Jr., Amer. Phot. 1926, ^0, 327. 
14 C. L. Gregory, Camera, 1926, 33, 122. 

Report of Progress Committee, 1926-1927 25 

15 H. S. Dusenbery, Camera Craft, 1926, 33, 412. 
»6 H. Riddel, Amer. Cine., 1927, 8, 6. 
" H. S. Dusenbery, ibid. 1926, 7, 11. 

18 M. P. Today, 1927, Feb. 5, 2. 

19 Ibid. Feb. 12, 3. 
2nbid. 1927, Mar. 5, 4. 

21 C. Ragum, Bull. Soo. frang. Phot. 1926, 68, 158. 

22 E. Wolff-Heide, F. P. 609, 398. 

23 Soc. Film en Couleurs Keller-Dorian, F. P. 606,601 . 

24 D. F. Comstock, U. S. P. 1,596,808. 

25 Soc. Film en Couleurs Keller-Dorian, F. P. 605,821. 

26 Ibid. F. P. 605,875. 

27 P. Fournier, F. P. 606,264. 

28 M. P. World. 1926, Nov. 27, 3. T. E. Finegan, Educat. Screen, 1926, 5, 

402; M. P. News, 1926, Nov. 20, 27; M. P. Today, 1926, Nov. 27, 10. 

29 J. N. Emery, Educat. Screen, 1926, 5, 460. 

30 J. G. McMillan, ibid. 1926, 5, 463. 

31 H. Wilbur, ibid. 1926, 5, 517. 

32 M. P. News, 1926, Oct. 9, 1373. 

33 R. Gaw, Educat. Screen, 1927, 6, 71. 

34 M. P. Today, 1926, Oct. 16, 2. 

35 H. C. McKay, Photo-Era, 1926, 57, 75. 

36 L. F. Conroy, Educat. Screen, 1926, 5, 329. 

37 M. P. Today, 1927, Jan. 22, 2. 

38 Ibid. 1927, Mar. 19, 5; M. P. News, 1927, Jan. 29, 2; Mar. 18, 954. 

39 M. p. News, 1927, Jan. 15, 2; M. P. Today, 1927, Apr. 2, 8. 

40 M. P. Today, 1927' Feb. 19, 4. 

41 Ibid; M. P. News, 1927, Feb. 4, 374. 

42 H. Kuhn, Phot. Rund. 1926, 63, 177. H. Foige, ibid. 157. 

43 Cleveland News, 1926, Oct! 6. 

44 Amer. Cine. 1926, 7, 6. 

45 L. A. Jones and J. I. Crabtree, ibid. 1927, Feb. 7. 

46 R. Namias, II Prog. Foto. 1926, 33, 72, 104, 134. 

47 E. P. 255,846. 

48 1. G. Farben Ind. A.-G. D. R. P. 431,634. 

49 R. F. Punnett, U. S. P. 1,600,736. 

50 S. E. Sheppard, U. S. P. 1,602,590. 

51 S. E. Sheppard and J. H. Hudson, U. S. P. 1,602,589. 

52 A. Ninck, Bull. Soc. frang. Phot. 1926, 68, 56. 

53 L. A. Jones, and V. C. Hall, J. Opt. Soc. Amer. 1926, 13, 56. 

54 S. E. Sheppard, Popular Astronomy, 1926, 34, 245. 

55 Bull. Soc. frang. Phot. 1926, 68, 148. 

56 W. Clark, J. Chem. Soc. 1926, 129, 749. 

57 L. Tranchant. Schweiz. Phot. Zt. 1926, 28, 240. 

58 M. Miyanishi, Mem. Coll. Sci. Kyoto Imp. Uni. 1926, Sept. 25. 

59 S. E. Sheppard, Phot. J. 1926, 66, 470. 

60 J. I. Crabtree and J. F. Ross, Trans. Soc. M. P. Eng. 1926, Nov. 26, 70. 

61 J. G. Capstaff and M. W. Seymour, Ibid. 1927, 10, 28, 223. 

26 Transactions of S.M.P.E., July 1927 

«2 L. Lobel, Sci. Ind. Phot. 1926, 6, 37. 

63 H. van Derhoef, U. S. P. 1,602,599. 

64 P. Strauss, Phot. Ind. 1926, 24, 801. 

65 F. B. Griffin, U. S. P. 1,596,965. 

66 Battle Creek Moon-Journal, 1927, Jan. 18. 

67 M. P. Today, 1926, Nov. 6, 2. 

68 E. Milani, Amer. J. Roentgenol, 1926, 16, 49. 

69 M. P. World, 1926, Oct. 9, 361. 

70 M. P. Today, 1927, Apr. 2, 17. 

" A. P. Richard, Bull. Soc. frang. Phot. 1926, 68,103. 

72 M. P. News, 1927, Mar. 11, 900; M. P. Today, 1927, Mar. 5, 22. 
72a M. P. News 1927, Mar. 4, 776. 

73 Ibid. 1926, Nov. 6, 1758. 

74 Kine. Weekly Supp. 1926, 112, 57. 

75 C. N. Bennett, Bioscope Supp. 1926, 67, iv. 

76 C. H. Frampton, U. S. P. 1,594,936. 

77 G. Seeber, Camera (Luzern) 1926. 5. 36. 

78 O. B. Depue, Trans. Soc. M. P. Eng. 1926, 10, No. 28, 242. 

79 Roscoe C. Hubbard, ibid. 252. 

80 RoUe, Kinotechnik, 1926, 8, 259. 

81 Apparatebau, D. R. P. 431,043. 

82 M. Vidaver, U. S. P. 1,604,138. 

83 V. C. de Ybarrondo, U. S. P. 1,592,407. 

84 K. Widemann, Phot. Ind. 1926, 24, 649. 

85 Amer. Cine. 1926, Dec. 19. 

86 L. A. Jones and C. Tuttle, Trans. Soc. M. P. Eng. 1926, No. 25, 153. 

87 M. P. Today, 1926, Nov. 6, 7; M. P. News, 1926, Nov. 13, 1848. 

88 Cleveland Plain Dealer, 1927, Feb. 21, 1. 

89 N. McCHntock, Trans. Soc. M. P. Eng. 1927, 10, No. 28, 279. 

90 G. E. Stone, ibid. 196. 

91 F. W. Haasis, Amer. Phot. 1926, 20, 414. 

92 M. P. Today, 1927, Jan. 22, 7. 

93 M. P. World, 1926, Nov. 20, 3. 

94 W. H. Glaser, Exhibitors Herald, 1925, Dec. 26, 32. 

96 L. T. Troland, Amer. J. Physiol. Opt. 1926, Jul. 375. 

96 W. E. Chamberlain and W. Dock, Radiology, 1926, 7, 185. 

97 J. Barot, Rev. d'Opt. 1924, Dec. 513. 

98 L. Lobel. Bull. Soc. fran(^. Phot. 1927, 69, 88. 

99 N. Y. Times, 1926, Nov. 21; Chicago Tribune, 1926, Nov. 21. 

100 Kme. Weekly, 1926, 116, 85. 

101 A. L. V. C. Debrie, U. S. P. 1,596,481. 

102 J. S. Milne, U. S. P. 1,598,357. • ' ^ 

103 U. S. P. 1,598,944; 1,597,013. 

104 Soc. Film en Couleurs Keller-Dorian, F. P. 605,882. 

105 P. H. Post, U. S. P. 1,601,260. 

J06 Yl S. Josephson, U. S. P. 1,598,914. 

107 C. Sylvester, Kine. Weekly Supp. 1926, 113,41, 43. 

108 M. P. News, 1927, Feb. 25, 698. 

Report of Progress Committee, 1926-1927 27 

09 Z. tech. Physik, 1925, 6, 661. 

10 Goldberg, Sci. Ind. Phot. 1926, 6A, 60. 

11 Kine. Weekly, 1926, lU, 87. 

12 L. A. Jones and C. Tuttle, Trans. Soc. M. P. Eng. 1927, 10, No. 28, 183. 

13 C. N. Bennett, Bioscope Supp. 1926, S, v. 
1^ H. E. Jodoin, U. S. P. 1,593,767. 

15 J. F. R. Troeger, U. S. P. 1,597,300. 

16 P. A. Congy, F. P. 610,040. 

17 L. Kepruska, E. P. 256,571 . 

18 M. P. News, 1927, Feb. 18, 566. 

19 M. P. Today, 1927, Jan. 22, 7. 

20 M. P. News, 1927, Feb. 11, 461. 

21 Ibid. 1927, Jan. 26, 294. 

22 M. P. Today, 1927, Feb. 26, 2. 

23 Ibid. 1927, Jan. 22, 7. 

24 Ibid. 1927, Mar. 5, 4. 

25 Ibid. 1926, Oct. 2. 

26 Ibid. 1927, Feb. 12, 4. 

27 E. J. Wall,Trans. Soc. M. P. Eng. 1927, 10, No. 28, 326. 

28 M. P. News, 1927, Feb. 25, 664; M. P. Today, 1927, Feb. 26, 2. 

29 N. Y. Times, Feb. 20, 1927. 

30 J. A. Rignon, U. S. P. 1,599,839. 

31 Soc. d'Exploitation d. Brevets et Proc. Bessiere, F. P. 608,614. 

32 C. Harriman, M. P. World, 1926, 81, 555. 

33 E. J. Dalcroze, Kine. Weekly Supp. 1926, 113, lU, Jul. 22, 53; Aug. 5, 53. 

34 T. Brown, Ibid. 1926, 113, Jul. 15, 61. 

35 M. P. News, 1926, Nov. 13, 1849. 

36 Ibid. 1926, Nov. 6, 1758; 1927, Feb. 11, 475; M. P. Today, 1927, Feb. 5, 2. 
3' M. P. Today, 1927, Mar. 5, 4. 
38 Amer. Projec. 1926, 4, Aug. 7. 
30 H. Kuchenmeister, E. P. 256,864. 

40 M. P. Today, 1927, Feb. 26, 8; M. P. News, 1927, Mar. 4, 793. 

41 M. P. Today, 1927, Mar. 26, 6. 

42 Ibid. 1927, Jan. 15, 6. 

43 A. DauvilHer, Compt. rend. 1926, 183, 352. 

44 Chicago Tribune, 1926, Dec. 31, 5. 


Mr. Gregory: In reference to the cine objectives, there are now 
two jfirms that have actually manufactured and are offering lenses of 
the claimed aperture of F/1.5. Mr. Minor, of Los Angeles, and some 
German makers are offering them. 

Mr. Griffin: In the report it is mentioned that ideal projection 
is being obtained in absolute darkness. The screen, mentioned in the 
report, will exactly reverse this procedure; the best projection can be 
obtained in a brilhantly lighted room. 

28 Transactions of 8M.F.E., July 1927 

Mr. Richardson: I might add that I have seen the picture, 
referred to by Mr. Griffin, projected. I stood in front of a well-Hghted 
window, within 6 or 7 feet of the window with sunhght outside and 
saw the picture very well indeed. It is proposed to project a perfect 
18 ft. picture with a lens of 2 in. diameter of less than 1 in. equivalent 
focus, and I think it will be done. 

Mr. Griffin: It is very easily perceptible; if the house lights in 
the theater are put out, the picture becomes very poor, and if the 
lights are put on, it becomes much brighter. 

Mr. Jenkins: I should like to ask how the information with 
regard to the pictures by reflection of infra-red rays was obtained. Is 
that a fact or something picked up? I understood that pictures had 
been projected through a lens with infra-red rays. 

Mr. Egeler: I believe you have in mind projection with regard 
to television. My information on most of this is obtained from refer- 
ences, and these are given in the report. 

The Board of Governors decided that a file of the Transactions 
should be bound and placed in the custody of the Secretary. Another 
bound file was to be placed in the library of the Engineering Society. 
It was found, however, that no copies of Nos. 1, 6 and 9 were among 
the back numbers in the possession of the Society, and an appeal 
was made at the Spring meeting for copies of the same. Two copies 
of Nos. 6 and 9 have since been presented to the Society and it is 
earnestly hoped that two copies of No. 1 may also be obtained. 
Should any member have surplus copies, or does not place great 
value on his copy of this issue, the Society will gratefully receive 
the same. 


THE Advertising and Publicity Committees were combined this 
year and it is obvious that this has meant considerably more work 
for those on the single committee. In spite of this, however, and 
many important changes in the equipment field which have reduced 
the number of concerns who helped us out in the past, the amount of 
advertising in the Transactions compares favorably with that printed 
other years. All advertising in the Transactions is given as a matter 
of good will and members of this organization are asked to help the 
Committee in the work of securing advertising for our publications. 
Personal solicitation by members of the Committee is a difficult 
matter and letters are cold and ineffective. The Society needs the 
funds secured through pubhshing a limited number of advertisements 
in the Transactions and if our members will say a good word for us 
the advertising departments of the companies they represent may 
be more willing to take space in our publications. The companies 
who have taken space are entitled to the appreciation of this Society 
and the Committee hopes that members of the S.M.P.E. will do 
everything possible to reciprocate. 

No systematic record has been kept of the publicity secured for 
the Society but the Committee believes that the officers and members 
of the organization are aware that the trade publications are devoting 
considerably more space to the work of the S.M.P.E. All these 
publications printed full accounts of our Conventions before and 
after the Fall meeting and have already published the full program 
of the Spring meeting. Some of the trade publications print papers 
from the Transactions in full and we hope to be able to supply 
abstracts of the papers read at this meeting so that they will become 
part of the news section of the trade publications while this meeting 
is in session. It is apparent that the motion picture industry is 
beginning to realize the value of the work of the S.M.P.E. and with 
the increased willingness of the Society to receive suitable publicity, 
your Committee has been able to work more effectively along these 

The Bulletin is also issued by this Committee and members of 
the Society are requested to make the fullest allowance for its short- 
comings. The work of issuing a Bulletin for this organization was 
entirely new to us this year and a four-page leaflet issued four times 


30 Transactions of S.M.P.E., July 1927 

a year does not offer much opportunity for giving the variety of 
information that insures the interest of all members of the Society. 
For a time it is difficult to secure any items and then at the last 
moment when the Bulletin is almost made up more good material 
comes in than we have space for. If the Bulletin is too formal there 
is a loss of interest and on the other hand this Society cannot very 
well afford to have the items published of too light a nature. Your 
Committee hopes to have the Bulletin issued six times a year to 
contain interesting information, official communications, the list of 
members and other printed material which does not properly belong 
in the Transactions. With these six issues of the Bulletin, four issues 
of the Transactions and two semi-annual meetings, members could 
be kept in touch with the Society practically every month of the 
year. It is important that contacts be kept up in this way as it is even 
more necessary for us to retain the interest of old members 
than it is to secure new ones. It is, of course, our hope that the 
Bulletin and other activities will help us secure new members for 
replacement and growth. 

While it seemed logical and correct to combine the Advertising 
and Publicity Committees as their work apparently lies along the 
same lines, your Committee is not so sure that the plan is an entirely 
satisfactory one. Solicitation of advertising and preparation for 
publication require considerable persistence and attention to details. 
Publicity work demands enthusiasm and some play of the imagina- 
tion. The qualifications necessary for securing advertising and 
publicity are not always combined in one individual and it is probable 
that better work in both of these departments could be secured if 
the Committees were again placed under different heads. 

P. A. McGuiRE, Chairman 

A. M. Beatty 

Louis Cozzens 

Geo. Edwards 

W. V. D. Kelley 

J. C. Kroesen 

John H. Kurlander 


ONE of the main difficulties encountered by the Committee is 
the remoteness of the printers, causing a lapse of at least a week 
before an answer can be received to any communication. Actually 
more time has been consumed in the transit of matter etc. than in 
the actual printing. This entails an inevitable delay in the appearance 
of the Transactions. Some slight improvement has been made in 
an earlier publication and more important still the root of the previous 
delays has been run to earth. It is, therefore, hoped that succeeding 
issues may appear somewhat more promptly after the meetings, 
particularly with the promised whole-hearted support of the Papers 
Committee to this end. 

Considerable work and time would be saved if authors would 
observe two simple rules: 

1. Never use single spacing in the typewritten MSS. 

Certain conventions as to spelling etc. are observed and errors 
are inevitable. These corrections can not be made with single-spacing, 
unless at least 2 inches blank spacing is left on each margin of the 

2. Do not send in a carbon copy of the paper. 

No less than three manuscripts had to be retyped because the 
copy was illegible in parts, mainly through the blocking up of the 
letters. Compositors are not mind readers nor decipherers of hiero- 
glyphics. That more mistakes did not appear is due to the fact that 
the reader of the MSS had heard the papers and carried some mental 
impression as to what was meant. But this means extra work and 
mental strain that are not conducive to rapid dispatch. 

By careful reading of the papers the cost of author's corrections 
— always a source of irritation and generally disputes between the 
printer and publisher — has been materially reduced; it is hoped that 
this may be maintained. To this end galley proofs of the papers were 
not sent to authors, except in one or two cases. This system will be 
continued and it behooves authors to see that their MSS really state 
what they meant. Alterations on galley proof, save correction of 
mere typographical errors, are not permissible — they cost money. 

Notwithstanding the fact that every typewritten copy of the 
discussions, sent to members taking part therein, bears a statement 


32 Transactions of S.M.P.E., July 1927 

that, if the same is not sent within 5 days to the Chairman of the 
Pubhcations Committee, he will correct and print the same, this has 
not been complied with by some members. This causes delay and 
correction in galley proof. This last too, costs money. It is earnestly 
requested that promptness in this respect be observed by all. 

E. J. Wall, Chairman, 
J. I. Crabtree 
K. C. D. Hickman. 


THE clerical work of any membership committee is interesting 
and not arduous. Whether a great increase in membership is 
secured is dependent on the new sources of possible members known 
to individuals on the Committee. During the past six months only 
one new source has been discovered and this by Mr. L. C. Porter. 
Mr. Porter had the great notion of sending in to the Committee the 
names of all persons inquiring for Transactions so that they might 
be circularized with the Society's literature. At least fifteen new 
members have been secured in this manner. Of the remainder eight 
more have come in by introductions from existing members of the 
Society, and four are in the process of admission. This makes an 
effective increase of twenty-seven. 

During a recent trip to Hollywood Mr. Crabtree and I secured 
the names of about three hundred technicians, mostly cameramen, 
who should be interested in our work. Experience early in the year 
has shown that the mimeographed form letter is instantly detected 
as such, cordially resented and consigned to the waste basket. These 
men are, therefore, now in the process of being written to individually 
and the results, if any, will be reported at the next Convention, thus 
concluding the year's work. At the moment it is interesting to note 
that the present increase of twenty -three net for the six months shows 
a very great improvement on the rate for the last three or four years. 

The membership of the Society will probably show a substantial 
increase owing to the successful efforts of Mr. J. A. Ball in founding 
a West Coast Section. At the moment we have no information as 
to the magnitude of Mr. Ball's undertaking, but doubtless a report 
will be forthcoming shortly. 

Committee Reports 


In conclusion it is interesting to study the appended graph com- 
piled by Mr. L. C. Porter showing the Society's membership curve 
from the date of its formation till the present time. 

From 1916 to 1922 the increase follows the normal law of organic 
growth. The number of members coming into the Society at any 
time is proportional to the size of the Society at that time. 

By 1922 all the available engineers had been brought in and the 
rate of growth necessarily falls off. The present new increase is 
indicative of the Society's excursion into new fields, and growth will 
probably continue till these too have given their available workers. 

K. C. D. Hickman, Chairman 
C. L. Gregory 
F. H. Richardson 

John H. Theiss 
W. C. Vinten 







Society of Motion Picture Engineers Membership 

1916 '17 7a 79 'ZO 'Zi '^;i '^3 14 'ZS '^6 '2.7 

YEAR (Fall Con vent ion) 


K. C. D. HiCKMAN* 

A GENTLEMAN (not myself) recently obtained an interview 
with the manager of a large picture corporation in Hollywood. 
He explained to his host -that while the corporation's films were 
excellent, everything about the business direction and technical 
economy was bad; that this should be altered here and that changed 
there ; that one man required dismissal and that another should be 
elevated to a position of command; finally, that what the company 
really needed was an engineering economist, of first class ability and 
reputation (himself) to set and keep things in order. 

To this the manager replied that half an hour previously the 
need for an economic expert had existed but his visitor's exposition 
had been so clear that all could be put in order without further 
trespassing on his time. The visitor departed a sadder and wiser man. 

This incident is typical of many. In spite of its isolation the 
wealth of Hollywood is such that people, important people, gravitate 
there from every corner of the world. They all want to induce the 
established powers to exchange part of their wealth for some com- 
modity — ideas, service, or interest — that they have to peddle. And 
the universal method of attack appears to be disparagement of things. 
Therefore, without having to step outside his office door, much less out- 
side of Hollywood, the company manager is made aware of every stunt, 
wheeze, or charlatanry relevant or irrelevant to the industry. Instead 
of having to establish contacts, his concern is to secure sufficient 
seclusion to get on with his job. Nor does the bombardment stop at 
interviews. The movie journals and magazines are alive with articles 
by publicists, novelists, and the louder species of technician describ- 
ing the errors of prevailing practice. In this sense, therefore, the iso- 
lation of Hollywood is legendary. 

There is, however, a humbler class of individual who drifts West 
doing the same real thing, looking for a job but without the blare of 
trumpets heralding revolution. Now it happens that in Hollywood the 
laws of supply and demand are curiously reversed, inasmuch as there 
is. an indefinitely great supply of technical and artistic labor and 
obviously a strictly finite demand. Yet salaries remain at an inflated 

* Research Chemist, Research Laboratory, Eastman Kodak Company. 


Hollywood and the M.P. Engineers — Hickman 35 

level. The explanation is that the demand is for the hest, always a 
select minority, and not for the cheapest. The trouble arises when one 
tries to assess the best. The best is often that which is rather than that 
which is purely speculative. The man that has a job has a means of 
expressing his ability and is therefore a more valuable commercial 
proposition than the man, be he ever so clever, who has no job and 
therefore temporarily no means of demonstrating his abihty. 

It follows that from the point of view of personal safety, silence 
and a certain measure of secretiveness is the first elementary protec- 
tive conduct of the successful movie technician; since during mere 
argument the man without a job fights on the same plane as the man 
in possession of one. Also, since there is keen rivalry as between 
studio and studio, reserve must be practised over technical working 
details. It is indeed a great tribute to the technicians that in spite of 
the immediate danger many are long-sighted enough to speak openly 
of their work, that bread cast upon the waters may return to them and 
their brethren after many days. 

From these disjointed remarks we may deduce an interesting state 
of affairs. While the whole world, whether from interested or altruistic 
motives is shouting advice to Hollywood, Hollywood herself is 
maintaining a discreet silence except in the legitimate business of 
advertisement. The world is telling Hollywood what Hollywood 
should do for the good of itself and the world; Hollywood fears to do 
anything but remain silent in telhng what she will need next year for 
next year's films; because each unit in telling the world will be telling 
neighboring units, each technical man would be telhng his brother 

In saying that the whole world shouts at Hollywood one must 
except a small but photographically important class to whom deeds 
mean more than words and whose very work precludes propagandist 
trips to the Coast. I refer to the photographic scientists; the chemists 
physicists, engineers, and opticians, the whole range of technical 
speciahsts in fact who at present constitute our Society of Motion 
Picture Engineers. You, who may claim to have more real knowledge 
to impart than boat loads of stunt merchants, are entirely out of 
touch with the people who consume the physical products of your 
brains. Out of touch in every medium save salesmanship, which 
professedly makes no attempt to convey scientific knowledge. 

Why do we want to keep in touch with the Coast? The answer is 
because we provide the raw materials of picture making : because our 

36 Transactions of S.M.P.E., July 1927 

livelihood, our right to hve (to use a fashionable phrase), depends on 
our ability to fill the movie man's needs in an ever expanding degree. 
To do this we have to do two things. We have firstly to disseminate 
continually and all the time general scientific knowledge, together 
with that practical instruction so prized by the field worker; and 
secondly, we have to get the other man to describe his business so 
that we may anticipate his needs of tomorrow. This is not a kindness 
nor even a duty. It is a commercial act as necessary as advertisement 
to a soap manufacturer. It is in no sense sinister but incorporates the 
best ideals of your Rotarians by securing mutual benefits from mutual 
interchange. We know this. The people out at the Coast don't. 

First of all, the few that have heard of us laugh when we call 
ourselves motion picture engineers. As well call the President the 
man who furnished the White House. We merely furnish the tools 
for the motion picture engineers. The real motion picture engineers 
may be seen in and around the studios and laboratories in Hollywood ; 
men whose names do not appear in our Transactions. I should like 
to call them primary motion picture engineers and ourselves sec- 
ondary motion picture engineers. This classification does not attempt 
to state their order of precedence, merely their order of function. 
Our present problem is to bring these two sides together and under 
the aegis of the Society. 

A short time ago the Chairman of your Papers Committee and I 
had the pleasure of spending a holiday in the West and being intro- 
duced to a large number of technical men and their parent organ- 
izations. Naturally we took every opportunity of urging membership 
by describing the Society's activities. To our pleasant surprise we 
found the ground had already been well covered by Mr. J. A. Ball, 
who had found a great deal of sympathy from the officials of the 
Motion Picture Producers and Distributors of America who promised 
secretarial and other help. 

All this is very much to the good, but nevertheless in our devel- 
opment we have to be very jealous even in our friendships. No young 
lady can receive a fur coat from a male friend without criticism even 
though everything may be alright. Therefore, though we have faith 
in every friendly overture, we must inquire what "Quid pro quo" 
will be demanded. I have said that firms on the Coast are being 
bontbarded continually with men and inventions purporting to work 
miracles. An ever-present problem is the sifting and weighing of these 
ideas so that the good may be retained and the bad rejected. The 

Hollywood and the M.P. Engineers — Hickman 37 

belief was expressed by a number of men to whom we talked that the 
S.M.P.E. in an enlarged and perhaps subsidized form would be the 
platform for technical court martials. 

This is not the first time we have heard the idea. The matter was 
debated very thoroughly in the discussion of Mr. Martin Quigley's 
paper at the last Convention. Suffice to say that the selection of the 
profitable from the useless, or more vulgarly "picking the winner" 
is the essence of business success, and the ability to do it is a valuable 
and highly paid quality. The firm to which I have the honor to belong 
has a staff of some hundred scientifically trained men presided over by 
a man of world-wide reputation whose job amongst others is to do this 
very thing — pass judgments. Yet I doubt if even he would care to 
make authoritative statements on the value of inventions to a third 
party. If the Society undertook such a function it would at once 
become a business institution of unlimited liability in which each 
individual member, be he ever so humble, would share equal re- 
sponsibility with the most prominent. He would be open to attack, 
prosecution, bribery, and every imaginable nuisance. Further, the 
Society would lose the most valuable asset of any living organism, 
freedom; would, in fact, cease to be a learned Society and become the 
instrument of the industrial group wielding at any moment the 
greatest power. 

Let us summarize therefore the things we want and balance them 
against our limitations : 

1 . We want an increase in membership because it gives us greater 
financial stability and freedom from heavy patronage; 

2. We want to draw the increase from the men engaged in 
primary motion picture work; 

3. We cannot expect these men to publish freely in our Tran- 
sactions because they are concerned with private technique rather 
than with fundamental science; 

4. Hence, at present the only blessing we have to offer them is 
the doubtful one of reading our Transactions, a blessing they could 
obtain at half-price by remaining non-members; 

5. They have, therefore, to be sold on the other aspects of 
membership; such as the ability to meet, make friends, and exchange 
ideas as between the primary and secondary types of motion picture 
engineers ; 

6. Since these abilities do not at present exist, our problem is 
to commence their manufacture. 

38 Transactions of S.M.P.E., July 1927 

Now, I ask you, unless we are very careful, will a West Coast 
Section alone meet the bill? If it remains a meeting ground for local 
technical battles, to be argued in private, and with no avenue for 
printed ventilation, it may serve a useful purpose but it would be 
no more affiliated with the Society than, say, the A.S.C. Since also 
it will have to retain part at least of its subscriptions for its own 
expenses, we might become entirely unconscious of its existence. 
We should then have been responsible for starting even another 
organization and served the cause of separatism rather than unity. 

To prevent this unhappy state of affairs, I can see only three 
remedies, two of them difficult and none of them novel. 

Firstly, precis, if not verbatim reports of all the discussions and 
talks occurring in the local section should be read at our Conventions 
and published in the Transactions. This takes care of the manu- 
facturing East sensing the needs of the user West. 

Secondly, at least one Convention in three should be held at a 
point so far west that the burden of getting there would be about 
equal from either California or New York State. And as a start off, 
even at the risk of a sadly depleted attendance from the East, a 
Convention should be held right in Hollywood. 

The third suggestion is an old one revamped, and concerns the 
tutorial lecture. W^here competition is so keen it is obvious that only 
technical men of some outstanding quality can occupy key positions 
in Hollywood. Yet it is a sad fact which they themselves are only 
too ready to admit that their knowledge is of a very empirical variety 
acquired by the pinch and handful methods of trial and error. Any- 
body who will stand up among them and give them quite elementary 
talks on, for instance, the inverse square law and stop values, or the 
nature of emulsion sensitiveness, which the research man erroneously 
believes to be common knowledge, meets, as we have found by 
pleasant personal experience, the warmest gratitude. There is no 
need to stress this aspect because our present program contains two 
or three papers expressly to meet the need. 

During the writing of this rather trite survey it has been pointed 
out to me that in things human as well as in things mechanical there 
are certain natural tendencies and striving to curb nature gives Httle 
result and. much friction. I am fully aware that if there is a natural 
gravitation of West Coast men to their own center any attempt 
of the parent body to force an artificial unity will be productive 
of nothing else than bad feeling. 

Holly wood and the 31. P. Engineers — Hickman 39 

However, we are men, and not fractious children, and we should 
realize the benefit of some sort of unity over and above the natural 
desire to be kings in our own castles. 

Therefore in penning this plea it is in hopes of being read by one 
or two at least of our new friends as well as being heard bj^ our old 
members. It is a plea to temper any new pohcies of self-determination 
with a profitable co-operation. 


Mr. Crabteee: I think the moral of. this paper is to hold a 
convention in Hollywood. It will have to come sooner or later. We 
all think we know a little as to what is going on in the industry but 
we don't unless we have been to Hollj^wood. The expense of such 
a trip would not be much more than it is to Norfolk. It would be the 
greatest advertisement the Society could have. It would tend to 
prevent the establishment of an entirely separate society inHollywood, 
which will happen unless there is more liaison between the East and 
the West. Incidentally, there is in process of formation, you might 
say, a much larger society than the S.M.P.E — what you might call 
a "cinematic" society — in which the engineer is only in a minority ; in 
other words, the society would include actors, scenario writers, and 
so on, and engineers. Once that society is established, I don't know 
where the Society of Motion Picture Engineers will fit. I think it 
very necessary for this eastern society to consider more thoroughly 
the matter of holding meetings in Hollywood and of getting more 
liaison between the East and West. 

Mr. Richardson: It costs me S24.00 to come down here and 
go back; it would cost me many times that sum to go to Hollywood 
and return. 

I have been in Hollywood several times and know that out there 
they consider themselves as about nine-tenths of the whole entire 
thing. I once listened to one of the big directors setting forth his 
views as to the relative importance of Hollywood and the rest of these 
United States. I gained the impression that outside of Hollywood 
only very small potatoes grew. I then looked the gentleman in the 
eye and said: "Yes, you chaps in Hollywood are very important. 
No doubt of that. But just the same any projectionist in any theater 
can, and many of them do utterty ruin and bring to naught all your 
skill and efforts. Your skill and work is all directly dependent upon 
theater managers and the projectionists for its final excellence in- 

40 Transactions of S.M.P.E., July 1927 

sofar as concerns the buying public. Put that in your pipe, friend 
director, and smoke on it for a while." 

Maybe we are the plumbers of the industrj^, but for the plumbers 
in real life we would pretty much all die, and without we motion 
picture "plumbers" and our expert "plumbing" the motion picture 
industry itself would soon languish and die. 

I don't think it is practicable to hold a meeting on the West Coast 
unless we want to hold alternate meetings, one on the West Coast and 
one in the East each year, permitting those who can make the trip 
west or east to attend both meetings. That might be the nucleus of 
an idea which could be worked out in successful practice. We might 
even manage two West Coast and two East Coast meetings a year. 

Mr. Porter: There seems to be considerable diversity of opinion 
on this Hollywood situation, but I believe the ultimate success of 
the Society depends on the formation of a strong section on the Coast. 
In the development of any industry in its organization you must have 
co-ordination, standardization, and our Society has done a wonderful 
work in that connection, but we are reaching the point where the 
technique of the questionable part of the motion picture industry 
is getting more or less standardized, and the future of the industry 
will depend more on the production of the pictures and on the artistic 
end than on the mechanical means, and I feel there will be an increas- 
ing need for a strong section on the Coast and perhaps a decreasing 
need for the work which we have been doing, invaluable as it is in 
the early development of the industry. 

Mr. Crabtree: We went out to Hollywood with preconceived 
ideas similar to those which Mr. Richardson has outlined. We were 
very agreeably surprised, however, to find that we were entirely 
mistaken as regards the technical man, that is, chief electricians, 
studio managers, men in charge of miniature departments, cameramen 
and laboratory men. We found these technical workers to be very 
modest people and very appreciative of any information which would 
help them in their work. Their degree of intelligence is of a much 
higher order than we had anticipated. Of course, most of the funda- 
mental research is being done in the East but much practical research 
work is being carried on out West. I think that the mental stimulation 
which would result from a visit to Hollywood would more than 
recompense every member for the slight extra expense involved. 

Mr. L. a. Jones: I have a very definite opinion on the subject 
which I have expressed frequently in the past at various meetings 

Hollywood and the M.P. Engineers — Hickman 41 

of this organization. It seems to me that we must face certain definite 
facts relative to the conditions which exist in the motion picture 
industry, conditions which have a profound influence upon the future 
of this organization. The motion picture industry is divided geo- 
graphically into two parts, there being a concentration of activity 
in the extreme eastern portion and in the extreme western portion 
of the United States. It seems to me quite impossible to say that 
either one of these two groups is more important than the other. 
They represent different parts of the whole industry and each is 
mutually necessar^^ to the well-being and prosperity of the other. 

I feel very strongly relative to the necessity of drawing into our 
organization those indi\dduals who are located on the West Coast. I 
feel that this is absolutely essential to the continued well-being and 
growth of the Society of Motion Picture Engineers. The question 
then is how can this be done. It seems to be quite evident that this 
entire group can not go out to the West Coast once or twice a year to 
attend conventions held there; Kkewise it is quite unreasonable to 
expect those who Hve there to come east once or twice a year to 
attend these meetings. In view of this it seems to me the only thing 
to be done is to reach some kind of a compromise. 

Would it not be well to consider the establishment of a West 
Coast Division of the Society which shall be of equal importance in 
every way to the East Coast Division. It is just possible that those 
indi\dduals who are located on the West Coast are not enthusiastic 
about becoming members of a section of a society the control and 
admim'st ration of which is concentrated in the east and which holds 
conventions twice a year which it is quite impossible for them to 
attend. I personally feel that I can sympathize with such an attitude. 
With two divisions each of equal importance and, let us suppose, 
eventually cf approximately equal membership it might be possible 
to hold one meeting a year in the east and one meeting a year in the 
west. It is possible that a few members of the western division could 
attend the eastern meeting and also that a few of the members of the 
eastern division could go west to the annual meeting of the West 
Coast division. I realize that this proposal is rather revolutionary. 
It seems for most of us in the east that we could attend only one 
meeting of the Society of Motion Picture Engineers each year. The 
great proportion of technical societies of national scope, especially 
those having relatively small membership, hold only one meeting 
per year. I reahze that many of us would feel very keenly the dis- 

42 Transactions of S.M.P.E., July 1927 

continuance of the present system which enables us to attend two 
meetings each year. However, if such a procedure is best for the 
organization as a whole I think it should be seriously considered. With 
such an arrangement the society would continue to hold two meetings 
per year and it would be possible for members of either group to 
present papers or to send papers to be presented at either one or 
both of the semiannual meetings. Our transactions would continue 
to be issued as they are at present following each semi-annual meeting. 
Or it is quite possible that with the additional membership such an 
arrangement might give us and the increased material for publication 
that it would be possible to publish more than four issues of our 
Transactions per year. I feel that there is no hope for this society to 
reach its highest development if we cannot in some wa}^ draw into 
our organization those individuals who are intimately associated 
with the motion picture industr}^ on the western coast. We must not 
only get them into the organization but make them feel they are a 
part of it and just as an important part as those who are located 
in the east. 

Mr. Richardson: That is the OTi\y really practical suggestion 
I have ever listened to on this subject. 

Mr. Hill: I am entirely in agreement with Mr. Jones on the 
matter that the two sections should be of equal rank. In view of the 
fact that we cannot attend the Pacific meeting in a body, we should 
have an official liaison officer. I think it would be acceptable for Mr. 
Crabtree or Dr. Hickman to do this. 

Dr. Hickman: With regard to Mr. Jones, I may say that I 
heartily agree with ever^^thing he said. I don't want to take part of 
the credit for his very excellent exposition, however, I must say I had 
not mentioned holding as many as one meeting a year in the West 
because I wanted to propose something acceptable to the Society. 
If the Society is reaU}^ making an effort to put the West Coast on the 
proper footing and go out there once a year, I think it an excellent idea. 

With regard to Mr. Richardson's remarks I can support Mr. 
Crabtree. People take you as you take yourself. If you go out there 
to test the feelings of the Coast, you will find a very hard, resistant 
front, but if you go out there humble with the intention of being 
useful you will find the people kind and obliging. They would give 
us a wonderful reception out there, because we demanded very Httle 
of them. 

Hollyivood and the 31. P. Engineers — Hickman 43 

With regard to time and expense, our convention here lasts 
three or four days: we spend two days of a week-end getting here, 
and most of us can get back Friday night. But how many of us go 
back to work before Monday? That same time would cover most of 
the journey from California. If you start Thursday night, you will 
get to California for the meeting Monday. I don't want you to think 
that Mr. Crabtree and I went to California sleeping in ditches or 
friendly Y.M.C.A's. We went at the most expensive time of the year. 
If we went on an excursion we could go and come back for $300. You 
can get good accommodation for $2 a day. .1 think it is a practicable 
suggestion that we go out West. 

Mr. McGuire: This organization should have more members on 
the Coast and they should indicate their interest in our work by 
attending meetings of the S.M.P.E. I am glad to state that as a step 
in that direction Mr. Cowling who is also a member of this Society 
is here as official representative of the American Society of Cine- 
matographers, Los Angeles, California. The American Projection 
Society is also represented through Mr. Lester Isaac, the Photog- 
raphers of the Motion Picture Industry by Mr. Carl Gregory and 
the International Projection Society by myself, all of whom are 
likewise members of the S.M.P.E. This is a new idea which I trust 
will work out and result in other organizations sending representatives 
to appear officially, who may or may not be members of the S.M.P.E. 
I hope that the whole question of holding meetings of the Society on 
the Coast can be submitted to all our members in order that we may 
get some idea as to how many would be able to take a trip of that 
nature. I have no doubt but that most of us would like to go. 

Mr. Richardson: Mr. Jones expressed my ideas on this. I 
don't retract one word I said, but my idea is that we should have one 
meeting East and one meeting West each year. The West Coast men 
will be able to attend one meeting a year and the western men will 
then probably maintain membership, but they will not do so with 
only one meeting in four or five years held there. 

Pres. Cook: Like many other matters which are discussed, 
no one knows what will happen until it is tried out. I think Mr. 
Richardson reflects the conscious attitude of about 80 per cent of the 
members here. In my opinion one meeting at the West Coast will 
settle the matter for all time, less than a dozen members will go 
and we shall make such a poor showing that the West will realize 
it is impossible for our membership to meet with them on any 

44 Transactions of S.M.P.E., Julij 1927 

common ground. I appreciate Mr. Crabtree's, Dr. Hickman's, and 
Mr. Jones' suggestions, but I do not think it will work out. 

Mr. Gregory: I am also here as a representative of the Inter- 
national Photographers of the Motion Picture Industries. 

Mr. Richardson: May I ask a question? Would it not be 
practical for the Board of Governors to get into communication with 
the Coast and find out their opinion of the suggestion made by Mr. 

Pres. Cook: We would have to do this in Governors' meeting, 
and as you are one of the Governors, Mr. Richardson, this would be 
in order at the next meeting. 

Mr. Porter: The general sentiment expressed here today seems 
to me equal for joint meetings; I don't see why that is necessary. 
I don't see why the West Coast Division cannot have as successful 
meetings as we have; I don't see why it is necessary to cover both 
the East and the West. It is done in other societies, such as the 
Illuminating Engineers and the Automotive Engineers. I don't think 
the success depends on joint meetings. I think they can have meet- 
ings as well attended and as successful as those here. 

Dr. Hickman: I want to remind Mr. Porter of the American 
Chemical Society, which has its section meetings, but all serious 
papers are always at the large national symposiums in gatherings 
from all parts of the United States. 

Mr. Porter: These national meetings to which you refer are 
made possible by large membership, and that is made possible by 
interesting local meetings. If we get a large membership on the Coast, 
the membership will be large enough to support a half dozen meetings. 
I think your interesting local meetings are the way to get membership. 


C. Francis Jenkins* 

THIS is not a learned technical paper. I simply am going to tell 
you about some of the fundamentals of Radio Movies and Radio 
Vision for home entertainment. 

And right here seems to be as good a place as any to begin 
standardizing the nomenclature of the new art. In our Laboratory 
we say Radio Vision when we mean seeing by radio, just as it is now 
common practice to say radiophone and radiogram, when referring to 
communication by radio. When we speak of wire-carried service we 
say telephone, telegraph, and television. Such definitions not only 
seem logical, and are euphonious, but they greatly facilitate accurate 
understanding in discussion. 

Similarly we say Radio Movies, when we speak of radio trans- 
mission from motion picture film, leaving the term Radio Vision 
to apply when we transmit directly from a person or a scene, although 
the same. machine is used in receiving the picture from either source. 

And perhaps I should begin my subject by saying that Radio 
Movies in the home will not hurt theater patronage. On the contrary, 
Radio Movies will stimulate attendance at the regular picture 
theater, for the analogous reason that the Victrola increased the 
number of grand opera patrons. Many of us came more intimately 
to know and to love the artists of the opera by familiarity with their 
personalities as recorded on Victrola discs. 

And I remember how Mr. Johnson begged the artists to permit 
him to carry the beauty of their talent to the far corners of the 
earth, appealing to their sympathy for the sick and shut-ins, and the 
lonely people of inaccessible places. 

Some artists entered the arrangement with misgivings, but to 
the astonishment of all of them their visible audiences increased with 
the popularity of their records, at the same time that their record 
royalties grew to exceed their income from grand opera engagements. 

Incidentally, may I refer to the sale by Mr. Johnson, a few weeks 
ago, of his talking machine interests for twenty-nine million dollars, 
at the end of twenty-nine years of belief in his idea. 

Perhaps it is only incidental to my subject, but I make the 
observation that people generally fail to notice the fact that a new 

* Jenkins Laboratories, Washington, D. C. 



Transactions of S.M.P.E., July 1927 

invention does not put an old device out of use. Every new invention 
finds its own field of usefulness while the old one gets added values 
in other lines. 

The coal oil lamp is generally assumed to have driven the 
candle out of use, yet ninety-five million gross of candles were sold 
in the year 1925. 

Visual Radio Home Entertainment 
The time is not very far off now when inaugural ceremonies, ball 
games, pageants, and other notable events may be seen reproduced in action 
on a small screen in the home, carried there by radio. 

The astounding increase in the use of electric fight might 
reasonably be supposed to have put both oil, and its successor, gas, 
out of business. But oil was never before mined in such quantity, 
nor gas used in such volume as now. Oil made Ford a very rich man, 
because he built a machine to consume an oil product, not as light 
but as power. Oil also gave our sweethearts the beautiful tints they 
wear. Made them beautiful so that we would love them; but left 
some of them dumb so that they would love us. 

I think that sometime I will also write a thesis on this subject 
as touching working people, who too often fear new inventions will 
make living harder for them. In fact it does just the opposite. Work- 
men burned up Compton's first power loom; destroyed Whitney's 
initial cotton gin; and broke up Howe's handmade sewing machine. 

Radio Movies — Jenkins 47 

It was a foolish thing to do, of course, for these inventions dress 
the workman better today than ever before, while he enjoys more 
conveniences and comforts. Why, even the cotton pickers now ride 
to the fields "in a Fode." 

America as a workplace is the envy of the world, and all because 
America's inventions have doubled the workman's output, shortened 
his work hours, and given him more of what he buys with a day's 

So, go easy now, don't condemn Radio Mo^4es; study the history 
of inventions instead. It isn't going to hurt theater attendance, it 
will increase it. If one only cultivates iii the public a liking for 
anything, habit will add its saving grace. 

Mr. Br^^an introduced the telephone to the public b}^ putting 
free phones in every drug store in Washington, a silent invitation 
to call up friends. Secretly I think we felt a little pride in using the 
new invention, and it cost nothing. A 3^ear later he put coin-slot 
boxes on the phones. And then there was a howl for sure. But we 
couldn't stop using phones, they had found a useful place in our 
daily habit. 

May I take a moment more to cite a case nearer analogous to 
Radio Mo\des in the home. Not far from my residence in Washington 
a picture theater was ha\dng a hard time because of poor attendance. 
When a friend of mine bought it I said to him : ' 'Harry, few people 
in this section of the city have the picture habit. Give me some pic- 
tures to show on my lawn every Saturday night this summer and I 
will build up a good attendance for you." And that is just exactly 
the way it turned out. 

But to get back to my subject — it, is time to give the public 
Radio Movies for home entertainment. The pubhc is ready; radio 
is ready; and movies are ready; and ever>^ element necessary to 
complete an acceptable machine is in hand. 

So the pioneer should be expected soon. I think he is due now. 
Doubtless Radio Mo\des will follow the same program other in- 
ventions have followed, hke film movies for illustration. 

And have you noticed that our own Society membership covers 
the entire range of the movies growth. There is the pioneer, Jenkins, 
if you will permit the presumption; then the explorer in the new 
thing, for example our own Gregory, who shows us the many tricks 
and avenues of applications possible with mo\des; Mr. Eastman who 
refines an essential in the new industr>^; Mr. Howell who produces 
splendid tools to work with; Power, Porter and Roebuck who give 


Transactions of S.M.P.E., July 1927 

us a standardized projector, through the projection aperture of which 
all the millions and millions of profits have come; then the co- 
ordinators who make a business of the whole, too many to name them. 

Daily Weather Maps are now available to ships at sea transmitted 
from Washington by radio. 

I have lio doubt but that Radio Movies will follow almost exactly 
that program. 

And Radio Movies will appeal with the combined mystery of 
radio and the fascination of the picture story in pantomime, guaran- 

Badio Movies — Jenkins 49 

teeing a permanent revenue never before equaled, for we all love 
picture stories, we never outgrow them. 

I have no doubt but that the Jenkins Laboratories would have 
finished Radio Movies last year except for the necessity of developing 
broadcast Weather Maps, to be picked up by radio aboard ships. 
This is now an accomplished fact, officially accepted and used by 
ships at sea and ships in the air. 

So it is hoped we may now resume the refinement of Radio 
Movies. There is no need to wait until some new element or principle 
is discovered, as has been claimed, for it is an accomplished fact 
now, and every^thing we need for its refinement is in hand. 

This was conclusively proved when on June 13, 1925, I demon- 
strated both Radio Movies and Radio Vision between the Na\y 
Radio Station NOF, at Bellevue, and my laboratories in Washington 

There were present at this demonstration, as I recall, Secretary 
Wilbur of the Na\y ; Admirals Taylor and Robinson, Captains Foley 
and Tompkins; Acting Secretary Judge Davis, of the Department 
of Commerce, and with him Radio Director W. D. Terrell; and Dr. 
George K. Burgess, Director of the Bureau of Standards. 

These gentlemen saw on a small screen in my laboratory in 
Washington, June 13, 1925, what was actually happening at the 
moment in the Navy Radio shack some miles away at Bellevue, 
across the river. 

A front page description of the demonstration was printed in 
the next day's Washington papers, the Sunday Star and the Sunday 
Post, and was broadcast by the Associated Press. It must have gone 
far, for I had a cablegram of congratulations Tuesday morning from 
a friend in Paris, France. 

And my demonstrations have shown that acceptable Radio 
Movies are easier to make than acceptable stills, principally because 
it is the story told in the movie picture, not its technical quality, 
which attracts. 

Perhaps, as engineers, you say: "But, you require such terrific 
speeds." Certainly, more than ten thousand times the speed for stills. 
So, as there are limits to mechanical speeds, we adopt the most 
practical speed for our purpose and then attain the necessary increase 
in speed by multiplying the light sources, which, sweeping across 
our screen, make up the picture. Already we have used four light 
sources, controlled by the pulsing of four corresponding light- 
sensitive cells at the transmitter; and carried by a single radio wave. 

"What, a single carrier. That is impossible." Certainly, I 


Transactions of S.M.P.E., July 1927 

admit that it is impossible, until one knows how to do it; just as a 
solid glass prism which changes the angle between its faces was 
impossible, until the development of the Prismatic Ring. 

j-irK<rr()N. d. c. srxhvy morxincx, jtxe 14. 1 






hex Foi- 


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We also find a fluorescent screen helpful, for its persistence of 
impression greatly assists persistence of vision. And brief persistence 
of screen impression is better than persistence of light source alone 

Radio Movies — Jenkins 51 

for the screen impression remains in its initial position, while per- 
sistence of light source moves on and dulls desirable sharpness in the 
screen picture. Although, in fact we use both methods on occasions. 

I have no doubt we could also give you music or speech with 
Radio Movies, or both sight and sound when in Radio Vision we 
transmit from living subjects or outdoor scenes, as from beautiful 
dancers, or an exciting baseball game. 

But who wants "talking movies." Except for its transient 
novelty, talking movies will, in my opinion, have no great or perma- 
nent attraction for the public. Quite likely recorded music will be 
substituted for the orchestra accompaniment to pictures. 

"Talking pictures" are an anomaly. If the pantomime picture 
tells the story, please, then, why the talk. It is with murder in our 
heart that we hear our next seat neighbor tell us what the story is in 
the picture we are looking at. 

All stories, as well as other facts, are recorded in our minds as 
pictures. It is a picture you pull out of your memory files, not a 
written description of a boyhood scene or activity. Even when we 
listen to a story we enjoy most the narrator who is the best "word 
picture" painter. 

With our eyes shut we make our best designs, for with lowered 
eyelids we close the curtains on all distracting scenes, as we build up, 
modify and finally accept our finished mental picture, before we 
transfer it to paper. 

So we shall not spend time on talking Radio Movies, leaving 
this work to others, for there are thousands of workers in audio radio. 
There will be occasions where audible radio will be useful, but they 
will be few where "talking" movies will be worth the added cost. 
So as time is short in any event, our task is straight Radio Movies 
and Radio Vision for home entertainment. 

In due course, then, folks in California and in Maine, and all 
the way between, will be able to see the inaugural ceremonies of 
their President, in Washington; the Army and Navy football games 
at FrankHn Field, Philadelphia; and the struggle for supremacy in 
our national sport, baseball. 

The new machine will come to the fireside as a fascinating 
teacher and entertainer, without language, literary, or age hmi- 
tation; a visitor to the old homestead with photoplays, the opera, 
and a direct vision of world activities, without the hindrance of 
muddy roads or snow blockades, making farm life still more attractive 
to the clever country-bred boys and girls. 

52 Transactions of S.M.P.E., July 1927 

Already audible radio is rapidly changing our social order; 
those who may now listen to a great man or woman are numbered 
in the millions. Our President recently talked to practically the 
whole citizenship of the United States at the same time. 

When to this audible radio we add visible radio, we may both 
hear and see great events; inaugural ceremonies, a football, polo, or 
baseball game; a regatta, Mardi-Gras, flower festival, or baby 
parade; and an entire opera in both action and music. 

This we shall soon take up for completion, and with the utmost 
confidence, for dollars and brains can do most anything. Brains 
sometimes without the dollars, but never dollars without brains, 
without the know-how. 

"But, Jenkins, when may we expect this wonderful buggy ride?" 
"Why, just as soon as I get the benzine to make it go, I've got the 


Prof. Wall: Are the results shown in half tone or silhouette? 
My reason for asking is that it was recently announced before the 
French Photographic Society that M. Belin had sent radio movies 
from Lyons, 300 or 400 miles away. The movement was said to be 
very slow and only silhouettes could be shown. By half tone I mean 
photographic half tone and not the dot pictures as used in illus- 

Mr. Jenkins: We can show either or both. Silhouettes are the 
easiest to send and are all that is possible on CW. To get half tones 
we are limited to a modulation set, although CW has many times 
the reach of the other. I think that some of you are aware that we 
have been sending half tone stills by radio for 6 or 7 years and are 
familiar with the system, and that to have radio movies means 
only increasing the speed of analysis. I mean photographic half tones. 

Mr. Richardson: What difference does a change in the speed 
of action make? 

Mr. Jenkins: This invention is going slowly from crude to 
better results all the time. In the beginning when higher speeds 
were involved in visual radio we took all the advantage possible. 
We ran the machines as slowly as would give us results, say, twelve 
to fifteen pictures a second, when the machine runs slowly, a slow 
performance gives better results. The problem is not greatly different 
from film in many ways. 


By D. L. Mistry 

EALIZING the importance of the dissolving shutter on pro- 
fessional cameras, I have devised the following simple types to 
be used on amateur cameras which have not been fitted with such de- 
vices primarily because of the added cost of manufacture. 




D & I 

Fig. 1. Plan and elevation of shutter dissolving mechanism. 

Main shutter shaft sprocket 
Counter shaft sprocket 
Idler sprockets 
Counter shaft 

Sprocke t frame 
Aux. shutter shaft 
Aux. shutter blade 
Counter shaft sprocket 
Aux. shutter shaft sprocket 
Main shutter shaft 
Main shutter blade 

same size 

same size 
and pitch 

The operation of the shutter is that of slowly advancing an aux- 
iliary shutter with respect to the main shutter, thus slowly closing 
or opening the open sector. This is done by linking a sprocket A 
Fig. 1 on the main shutter shaft with a sprocket 5 on a countershaft 
C by a chain D which also passes over idler sprockets E and F. The 
spindles of sprockets E and F are carried on a rigid frame which may 



Transactions of S.M.P.E., July 1927 

rotate about the countershaft C. Mounted on the countershaft C is 
a second sprocket H hnked by a second chain / with a sprocket / 
on a tube K coaxial with the main shutter shaft .and carrying the 

Fig. 2. 


Main shutter shaft sprocket 

same size 


Counter shaft sprocket 

and pitch 


Counter shaft 




Idler sprocket 



Idler sprocket 



Sprocket frame 


Aux. shutter shaft gear 

same size 


Counter shaft gear 

and pitch 


Aux. shutter blade 
Main shutter shaft 


Main shutter blade 

auxihary shutter L. The sprockets are of such sizes as to give the same 
speeds to the two shutters. The shutter combination is geared to the 
camera in timed relation. 

The operation of the shutter is as follows: As long as the frame 
G has a fixed relation to sprocket A the shutter will have a constant 

Dissolving Shutter — Mistry 55 

angle of aperture. If, however, the frame be moved in relation to the 
sprocket A the relative angular positions of sprockets A and B will 
be altered and accordingly the relative positions of the two shutters 
L and N changed, since shutter blade N is fixed in relation to sprocket 
A, and shutter blade L is fixed in relation to sprocket B. Thus for a 
fade-in the frame is moved gradually to the right, and to the left for 
a fade-out. 

The mechanism can be varied in a number of ways according to 
the adaptation to the particular camera. For instance, as in Fig. 2, 
the sprockets H and J, of Fig. 1, may be replaced by gears in mesh 
and sprockets A, B, E, and F, linked by a chain as shown in Fig. 2. 
The aperture may be altered by moving the carriage G from the right 
to left. The hollow shaft may also be eliminated. 

A similar device may also be applied to the feed and take-up 
sprockets of a projector to adjust the loops. It may also be applied 
to the shutter drive and used to adjust the timing of the shutter in 
order to remove "travel ghost" while the projector is in operation. 

In conclusion, let me call the attention of the Society to the need 
of a compilation of the art of the industry in the form of an encyclo- 
pedia or an equivalent form giving a ready reference to all that has 
been accomplished from the beginning. 

Hyper-sensitizing cine film. — MM. Gibory, Bachelet & Berliet 
have used with marked success the following method of hyper- 
sensitizing film: 

Pinachrome, 1:1000 ale. sol. ^ 15 ccm. 

. Pinacyanol, 1:1000 ale. sol. 8 ccm. 

Methyl alcohol 40 ccm. 

Distilled water 1000 ccm. 

The film was bathed, on silvered frames, for 3 minutes in the dark, 
then washed for 1 minute in running water, immersed in an 8 per 
cent solution of strong ammonia, again washed for 1 minute and 
dried on a drum. Development was effected with glycin after 2 
minutes desensitizing with basic scarlet N, This method was found 
to more than double the speed of the film and it would keep 2 weeks. 
(La Cinemat. Frang.; Filmtechnik, 1927, 3, 148). 



H. I. Wood.* 

LIKE so many of the good things of present day industry the 
light source described in this paper is the product of the work 
of a number of different investigators over a considerable period of 
years. The principle is not new, but it is only with increased knowl- 
edge and with improved materials of recent times that the present 
results have been possible. 

From the beginning of the motion picture industry, the equip- 
ment manufacturers have been calling ever for ''more light" and no 
sooner have the lamp manufacturers met any set requirements than 
the standard has been raised. We feel now that we are perhaps a lap 
ahead and consequently are glad to take this opportunity to present 
our achievement. 

The standard construction of a coiled filament operating in an 
atmosphere of inert gas — the Mazda C lamp — is now universally 
known. By coiling the filament its effective length is brought down 
to about 10 or 15% of the straight wire length. This permits a much 
greater concentration of the light source. But there are limits 
beyond which it is not possible to go. There must be a definite mini- 
mum separation between the segments or there will be either arcing, 
or short circuiting, due to almost unavoidably slight warping or 
twisting. Also it has not been found commercially possible heretofore 
to produce a projection lamp of less than 100 watts in the 115 volt 
range and even this lamp requires our most skilled operators. 

The lamp described below has allowed us to go a step further. 
Starting with the regular coiled filament it is again coiled, making 
what we have designated as the "coiled-coil" filament. This has 
made a further reduction in the effective length to about 25% of 
the coiled filament or to approximately 3% of the length of the 
straight wire. The resulting filament can thus be concentrated into 
a still smaller area. Actually as shown in Table 1. this area for 100 
watts is reduced to less than half. There are, of course, definite 
limits to this new construction. The separation of the segments 
must be kept wide enough to prevent arcing — possibly somewhat 
wider than with the coiled filament, for, with fewer segments, the 

* Incandescent Lamp Department of the General Electric Company. 


A New Light Source — Wood 57 

maximum voltage across any two adjacent points is higher and the 
arcing tendency more pronounced. Further, as the diameter of the 
coil becomes greater, the front portions block off part of the light 
from the rear portions and prevent its getting through to the con- 

Some advantages of this construction are: 

1. A greater concentration of light source. This can be utilized 
by either retaining the wattage and lumens and putting them into a 
smaller area or by retain ing the area and putting into it more wattage 
and luminous area; 

2. The possibility of a commercial projection lamp of 50 watts 
in the 115 volt range; 

3. A lamp in the 115 volt range with approximately the same 
light source area that is now standard in a lower voltage. 

In connection with the last two points, attention is called to the 
fact that it has been customary in some instances to use a low 
voltage lamp with series resistance. This means, on one hand, a loss 
of energy to the user, and on the other, the need in the equipment 
of an additional piece of apparatus, increasing the cost and sales 
price. While neither of these items is of great importance for the 
smallest sizes, it becomes of some moment in lamps of 200 watts or 
over. Another item not to be overlooked is that with a low volt 
lamp and regulating resistance it is not easy to adapt this combina- 
tion to all conditions of voltage found in various central stations 
(unless an ammeter is employed) . The lamp may thus be operating 
above its normal voltage and so give the user short life, or it may be 
under voltage and give poor screen illumination. With the 115 volt 
type, a lamp of the correct voltage can ordinarily be used and both 
difficulties avoided. In order to prevent any misunderstanding it 
should be noted that in changing from a 50 volt to a 115 volt lamp of 
the same wattage, there is some loss in total lamp lumens as the 115 
volt filament is of smaller wire size and so must be operated at some- 
what lower temperature. 

Before presenting figures for screen tests on the various wattages 
it may be of interest to show some of the steps used in the manu- 
facture of the coiled-coil filament. These are shown for a 200 watt 
115 volt lamp in Fig. 1. A is the regular coiled filament with the 
mandrel on which it was wound still intact. B shows the next step 
where the coil A is being wound onto the second mandrel. C is the 
coiled-coil formed into shape, after which it is heat-treated and the 

58 Transactions of S.M.P.E., July 1927 

mandrel wires dissolved. It is shown in the finished form ready to 
go into the lamp at D. ^ is the regular coiled filament of the same 
wattage and is shown to compare the relative dimensions of the 
two types of filament. Fig. 2 shows the finished lamp. 

As shown in Figs. 1 and 2, the coiled-coil filament in the 115 
volt range is made with 3 segments. This is partly because of the point 
mentioned earlier, that with the greater concentration the arcing 
tendency is greater. With the 3 segments the points of maximum 
voltage are on the diagonal of the filament, which is the greatest 
distance possible with a given concentration. 

Fig. 1 

Table No. 1 summarizes figures obtained in our Engineering 
Dept. with several sizes of the coiled-coil filament and, for comparison, 
coiled filament lamps of the same wattage. The optical system used 
for these tests consisted of a standard 16 millimeter aperture, a three 
element condenser, an objective of about F 2.25 speed, and a mirror, 
all accurately set on an optical bar. This system was chosen as it 
is similar to some in commercial use. 

The comparison is made on the basis of equal watts and equal 
life-. It may be well to point out that while the customer, under 
service conditions, would not secure the same results as shown in 
the table the relative values would be similar. There might even be, 

A New Light Source — Wood 


in some cases, a greater gain by the use of the coiled-coil filament 
lamp. For instance, if an optical system was designed to make use 
of the smaller source area, an additional gain might reasonably be 

Table 1. Relative Sa^een Illuminations and Source Data 
for Coiled-Coil and Coiled Filament Larnps. 

Light Si 

mrce Screen 


% Increase 

Lamp Rating Area-Sq 

. mm-. C.C 




C.C. over C. 

Watts Volts C.C. 



Mirror Bare 


Bare Mirror 

50 115 18 






— — 

100 115 25 



35 14.5 


59 52 

200 115 49 



66 32 


34 20 

200 50 33 



70 ^ 



-4 -5 



Fig. 2 

On the second hne in Table 1. is given the data for the 100 
watt 115 volt lamp. As shown in columns 3 and 4 the light source 
area of the C.C. (coiled-coil) filament has been reduced to less than 
half that of the C (coiled) filament. The screen lumens are given in 
columns 5 to 8 and the percentage increase with the coiled-coil 
filament in the last two columns. This increase is approximately 50%. 

60 Transactions of S.M.P.E., July 1927 

By "Bare" is meant the light projected with the mirror removed, but 
the rest of the setting identical. 

On line 3 is the data for the 200 watt, 115 volt lamp. This shows 
a smaller reduction for the light source area than with the 100 watt 
and correspondingly, a smaller increase for screen lumens, though a 
marked gain. 

The last line — 200 watt, 50 watt — shows slightly lower screen 
lumens with the coiled-coil filament. 

Tests (not shown) have been made on lamps of higher wattage 
but they have not indicated, with the 16 mm. aperture, any marked 
increase over the 200 watt lamp. 

Other forms of projectors, using larger than 16 mm. apertures 
and projectors such as spot lights, search lights, stereopticons, etc. 
have not yet been tested. Knowing the effect of smaller light sources 
on such systems, it seems reasonable to expect marked advantages 
when higher wattage lamps have been developed. 

To summarize: This new light source has permitted us to offer 
a 50 watt, 115 volt, projection lamp; it will give an increased screen 
illumination of about 50% for the 100 watt lamp, and 20% for the 
200 watt lamp. It does not yet offer advantages for lamps of higher 
wattage, or of low voltage when used with a 16 mm. aperture. For 
equipment using larger apertures, and for projectors like the spot 
light it seems reasonable to expect a material improvement from 
higher wattage lamps, when they have been developed. 

Another Hyper-sensitizing Process. — Two Berlinese (Germany) 
investigators, Moise Safra and Reimar Kuntze, have it is announced, 
made a wonderful discovery by means of which an interior set may 
be taken by the light of a single incandescent lamp. For outdoor 
work it enables one to take dark woodland scenes, late evening and 
night effects. This wonderful result is attained by passing the film 
through a certain chemical bath. The only disadvantage is that the 
film must be used within a month; "but it is hoped to overcome this 
defect as preliminary experiments have proved this to be possible." 
According to the inventors excellent results have been secured of a 
group illuminated by red light only. (Le Cineopse, 1927, 9, 341) . 



By Fred Waller* 

HE field covered by this title is so large, that I have selected 

for this paper samples of only four of the many lines along 
which this work is pursued at the East Coast Studios of Famous 
Players-Lasky Corporation : 

First, the' Storm Episode from the Gloria Swanson picture, 
"The Untamed Lady," which is a reproduction of a natural scene in 
miniature; second, the episode showing magazine illustrations coming 
to life, from "The American Venus," directed by Frank Tuttle, which 
is really the reverse of a miniature shot; third, the delirium scene 
from the Thomas Meighan picture, "Blind Alleys," which is the 
production of a psychological effect ; fourth, the coach going through 
the gates of Heaven, from "A Kiss for Cinderella," directed by Her- 
bert Brenon, producing a purely imaginative scene. 

These four scenes have been selected not only for the different 
effects produced, but also for the different technical, artistic and 
dramatic problems which were involved in their production. 

The most important part in the production of an illusion is the 
planning of the scenes and the determining of the particular methods 
to be used. Unfortunately, it would consume too much time to recite 
this in full. I will, however, give you an outline of this part, as well as 
the mechanical work done. 

The Storm at Sea. 

The problem here was to produce an effective, realistic scene of a 
storm at sea to cut in with the action made of the real people in the 
studio, and to do this in as small a scale as possible. 

It was desired in the picture to show the boat returning home 
after the storm in a disabled condition and some prominent portion 
had to be destroyed. It was decided that the fore-mast should be 
struck by lightning and this had the additional advantage that the 
lightning flashes illuminated the scene and showed the wind gusts 
more clearly. 

To determine the scale of the model, some simple experiments 
were made, and it was decided that 5/8 inch to the foot would give us 
a good long shot effect of breaking waves. This scale required a tank 
* Famous Players Lasky Corporation. 


62 Transactions of S.M.P.E., July 1927 

40X60X5 feet deep. Two models were constructed and used in this 
same tank, one in 5/8 inch scale for the long shots and a partly-finished 
one in 1 inch scale for the close-ups. On this 1 inch scale model only 
the bow of the boat and the stern propellers were ever shown in the 
picture. The over-all length was 15 feet. 

Previous experience had shown that towing boats by an invisible 
wire, or running them on a track, gave an unnatural movement and 
therefore the 5/8 inch model, which was actually 8 feet long, was 
equipped with two small high-speed motors actually driving sub- 
merged propellers, and connected through a rubber-covered electric 
cable which the boat towed, to a control board at the end of the tank. 
The connections made through this cable also lighted the lights on 
the boat and controlled a solenoid which operated release triggers on 
the six shrouds supporting the front mast and also a dowel pin which 
was inserted in a break previously made in the mast. This allowed us 
at will to let the mast blow away and fall overboard, and to steer 
and control the speed of the boat without ever touching it. 

This little model, under its own power, actually pushed its way 
up against the three-foot waves and the wind from four airplane pro- 
pellers, without any assistance. 

Most miniature shots can be detected by the unnatural appear- 
ance of the water. Therefore, the next problem was to produce the 
correct type of breaking wave. This was solved by designing four 
special wave machines which were used at the right-hand side of the 
tank. Their construction was of solid wood and they each weighed 
about a ton. They were formed so as to present a 4 foot surface at a 
45° angle to the surface of the water, so that when they were raised, 
the water would rush under them, and when they were lowered against 
this inrush, they would move the water faster at the surface than at 
the bottom of their stroke. These heavy wedges were actuated by 
long levers and as all of the scenes took less than a day to photograph, 
it was cheaper to use man-power than to install mechanical means for 
doing it. It may be of passing interest to note that it took twenty-four 
men to produce the waves. 

This effect, accompanied by the wind on the surface, produced by 
the airplane propellers, gave a fine, tumbling wave. Still further 
invention was necessary, however, for if this wave was allowed to 
strike the flat wall on the far side of the tank, part of it would rebound 
and spoil the effect of an open sea. Consequently, a wave absorber 
was built, in the form of layers of heavy wire mesh supported on 

Illusions in Cinematography — Waller 63 

timber bracing and covered with fine wire mesh, twelve layers being 
put about 4 inches apart and extending to the bottom of the tank 
running the entire length of the tank, which was 60 feet. The action 
of this was to cause so much resistance to the waves, that by the time 
they passed through these layers and back again, there was no real 
disturbing effect. 

Even a photographic backing presented a slight problem, as it had 
to be waterproof and of such a texture as not to show where the sur- 
face had wet it, and be built solid enough so that the waves would not 
tear it loose. This was met by a gray waterproof backing, 20X40 
feet, painted on heavy canvas with a paint which was a combination 
of oil and water pigment. This backing extended to the bottom of the 

To give a satisfactory night effect and still show the rain and gusts 
of wind, only a small amount of front light was used. Most of the 
lighting was back light on the rain with only part of this striking the 

The dimmer lightning flashes were produced by shorting an 
electrical circuit, which is the standard studio practice. 

The more brilliant flashes were put in by staining frames of the 
negatives with an anilin dye of a non-actinic color. The forks of 
lightning were put in on the negative with an extremely fine pen and 
an opaqu'e ink, timing the progression and skipping frames to give a 
realistic effect. 

The production of a good rain effect necessitated the combination 
of extremely fine needle sprays directed in the path of the airplane 
propellers and clouds of nebulized Nujol to represent the blowing 
spray which accompanies every gale. 

The cameras were set at a very low level so as to give height to the 
boat and waves. At the end of the tank which was somewhat pro- 
tected from the waves, pieces of plate glass were inserted to photo- 
graph through. A cranking speed varying somewhat with the length 
of the shot and running from eight to twelve times normal, i. e., from 
128 to 192 pictures per second was decided upon. This gave the three- 
foot waves the necessary timing of thirty-foot ones, while the mast 
appeared to fall slowly as a large mast really would fall. 

Magazine Illustrations Coming to Life. 

The scene the director desired was bathing girls illustrated in a 
magazine becoming real and stepping out and performing on Ford 

64 Transactions of S.M.P.E., July 1927 

Sterling's desk as he is admiring them. He orders them back as his 
puritanical wife appears on the scene. 

The most important thing here was realism. Anything which the 
audience might detect as being artificial would greatly detract from 
the episode as a whole. It was decided that a complete illusion could 
be produced by cutting in close-ups of Ford Sterling and using four 
different methods of showing the book. 

To do this, a desk top was built twelve times as large as the real 
desk appeared in the original scenes in the picture. The penholder, 
desk pad, letters, etc., were all built on the same scale. 

The camera was placed in the same relative position as a man's 
eye would be. This figured out to be about 20 feet from the back of the 
desk, and 16 feet above the writing pad. One of the problems was to 
get enough light for a full exposure and still have it possible for the 
girls to act normally without being blinded by the light. Fortunately, 
we were aided in this by the fact that a small figure should move 
quicker than a large one, therefore a cranking speed of about eight 
to ten pictures per second was used for most of the shots. The 
reason for the light difficulty was the extremely small aperture neces- 
sitated by the depth of the photographic field, as the man's hand 
which appeared in the picture was only 3 feet from the camera, and 
the small figure on the desk was over 20 feet from the camera. 

The normal-size magazine was made out of photographs printed 
on matte-surfaced paper, the photographs being still reproductions 
of the large pages with the girls standing in them in the same place 
as they appeared when first seen in the film. 

The methods used in photographing the action of the girls and 
the magazine pages so that it would not be obvious to the audience as 
to how it was done were : 

First where the hand opens the book and the girl steps down from 
the illustration, only half of the magazine was built in large scale, 
three pages of a small magazine being mounted on the glass 3 feet 
from the camera in registration with the enlarged page which the 
girl was standing against. As the hand opened these pages, the en- 
larged page with the girl in front of it was disclosed, and the registra- 
tion and lighting made it look like one complete book. 

Second, the next girl steps out from behind a page, which is made 
of quarter-inch beaver board, purposely made curly, covered with 
muslin on both sides, and painted in scale to look like a page of a 
magazine, the left-hand side still being the normal size book near the 

Illusions in Cinematography — Waller 65 

camera. This same method was used for the page which was opened 
by the first girl, disclosing the third one standing motionless. 

Third, the page which was apparently kicked open by the third 
girl was a normal-size magazine page, which was really 17 feet away 
from her. This page was a photograph of the background on which 
the second girl stood, placed beside the left-hand side of the book on 
the glass close to the camera. Here a little ingenuity was necessary. 
This page must be opened quickly, bulging out in the center as though 
pushed by a foot, but without any visible means of moving it. As 
this page was only 3 feet from the camera, the finest thread or wire 
possible would have shown, so a jet of compressed air was used and 
proved very successful. With a little rehearsing and timing, the girl 
carried out a kicking gesture simultaneously with the blowing over of 
the magazine page, thus making a very realistic effect. 

Fourth, in order to give the girls more scope for action and to 
prevent the audience from realizing that there might have been 
small pages used in this set-up, the left-hand side of the book was 
built in large scale and the glass removed. 

Naturally, these different methods could not have been combined 
if all of this action had been played in one continuous scene. However, 
an episode hke this is not only more convincing but much more enter- 
taining if you cut back to the principals in the picture and make them 
a more intimate part of the episode. 

The end of the episode where the girls are ordered back by a ges- 
ture of the large hands into the book and one of them gets caught, was 
done in combination with the small book on the glass, as in the first 
method, but considerable care in timing the action of the girl was 
necessary to make it look as though the page had actually hit her. 

The Delirium Scene. 

This episode was to depict what would take place in a delirious 
man's mind, who had been struck by an automobile and separated 
by this accident from his bride. 

The place at which this action occurred was Broadway and 44th 
Street, and it seemed logical that the man would confuse the rushing 
automobiles and the swirl of lights as he became dizzy from the im- 
pact. His wife appeared to him through the confusion, and finally 
restored his composure. 

A sequence like this could be done directly in the camera running 
the film through seven times and with mats covering up all of the 


Transactions of 8.M.P.E., July 1927 

different sections that the additional exposure should not appear on. 
However, the length of time necessary to work this out on the stage 
and the chance of error was so great that it was decided to do this 
entirely by making a duplicate negative on a projection printer espec- 
ially designed to do trick work. Therefore, the scene of Mr. Meighan 
in bed, which was the key negative for the series, was made in the 
studio in the normal way, and this required no special treatment 

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except space around the figure in which to place the additional action. 
Then a negative was made at night on Broadway, with a camera 
mounted close to the ground on a revolving mount, so that the effect 
of a whirling mass of lights was produced, and several scenes of auto- 
mobiles taken from different angles and with different action, were 
made; also a scene of his wife made against black velvet. 

Prints of all these scenes were made and were cut so as to secure 
the best parts of each. Then a chart (See Figure 1) was made showing 
the different positions in which each of these was to appear over the 
key negative with varying lengths of fade-ins and outs, and varying 

Illusions in Cinematography — Waller 67 

On the projection printer, a test print showing several different 
densities was made from each negative and from this the correct 
exposure for the different effects was selected. These tests, of course, 
were developed simultaneously in a developer of a given strength and 
at a given temperature. Scenes which were not to appear in the same 
part of the finished dupe were combined in the projection printer on 
the positive. This reduced the number of times that the finished dupe 
would have to be exposed. 

The next step was to make a duplicate negative from the key 
scene of Mr. Meighan varying this exposure as per our chart, and on 
to this exposed negative before development, negative impressions 
from the other four positives were successively exposed each of which 
contained one to three scenes. 

This method may sound very intricate but the great advantage is 
that the time of a stage unit is not taken up to perform this very 
technical job. Only one or two men are needed to work on laying it out 
and printing it, in a little separate laboratory. Not the least advantage 
is that if the position, timing or exposure is not satisfactory, it is 
simply necessary to change the chart and make a new print and dup- 
licate negative, as none of the individual scenes has to be remade. 
The most important point of all, however, is the perfection in timing 
and selection made possible by this method. 

For these seven scenes, about four takes each were made and the 
best ones selected from a print. Then the best parts of the selected 
ones were cut and joined together in the regular manner. This film 
was run many times to complete the cutting and alter the timing. 
From this the aforementioned chart was made. 

To have secured this degree of perfection in the camera would 
have been very nearly impossible. Consider mathematically just the 
selection of scenes: the chances would be the 7th power of 4 against 
1 for getting all this perfection in one take. 

It is, of course, necessary that this type of work be done with 
extreme accuracy. Great attention should be paid not only to 
precision in the machinery but to cleanliness and care in handling the 
negatives and to uniformity of quality in laboratory work, so that the 
finished result will be of good standard quality. 

The chart, shown as Fig. 1, will give you an idea of the method 
whereby the different scenes were used. 

68 Transactions of S.M.P.E., July 1927 

The Coach Going Through The Gates of Heaven. 

Mr. Brenon desired to depict in this scene the idea which a little 
English slavey would have of a trip through the gates of Heaven in a 
coach drawn by four white horses. Sketches and wash drawings were 
submitted to Mr. Brenon suggesting different final effects to be 
obtained, without regard as to how they were to be done. Upon his 
selection, we proceeded to figure out the most economical and 
efficient method consistent with quality and in this instance, great 
speed, because due to some other circumstances, this had been post- 
poned up to within a short time of the release date for this picture. 

For a great portion of this work, multiple exposure would have 
been possible but this would have meant delay in screening the final 
scene and a chance of error, and at this time our projection printer 
was not finished. Therefore, it was decided to use several planes of 
action combined in a single exposure. 

The first practical consideration was how steep a hill could four 
horses draw up a coach without seeming to labor too much. It was 
foiind that this angle was not nearly steep enough to give the desired 
effect, so a ramp or runway was built on which the horses could get a 

Illusions in Cinematography — Waller 


running start downhill before they entered the picture and then 
proceed up an incline at a 12° angle. As an angle of 27° was needed 
in the picture, the camera was tilted the necessary additional amount. 
In Fig. 2, the angles of the ramp and camera are shown. Fig. 3 
is a ground plan of the set, which was in a football field hired for the 

Starting from the camera the different photographic planes which 
were brought into registration to make this scene were as follows: 



FIG. 3 



^^^^^^■»rj !^_ 






Three mo\dng glasses with clouds painted on them, the glass 
nearest the camera moving the fastest, the next one at a middle speed 
and the third one the slowest, so as to give movement perspective. 

The fourth plane was a fixed glass, on which was painted the 
arch in which the gates swing, the pathway through the clouds and 
the temple beyond the gates. In the painting on this glass there was 
an opening left for the gates and the lower far side of the archway. 
Also an open space for the coach and horses to mount through. 

The fifth plane was a pair of miniature gates mounted in position 
to register with the fourth glass and arranged to swing open with 
hidden levers. 

70 Transactions of S.M.P.E., July 1927 

The sixth plane was a backing behind these gates to correspond 
with the cloud effect on the fourth glass. 

The seventh plane was the actual coach and horses running on the 
blackened surface of the ramp, backed by black velvet drops 20 feet 
high and totally 200 feet long. 

The eighth and last plane was a small built section of the portals, 
built just high enough to cover the height of the coach, and made to 
exactly match with the balance of the portals which was painted on 
the fourth glass. 

For the desired effect, it was necessary to light these different 
planes of action entirely by artificial light and therefore these scenes 
were done at night. The front glasses were hghted by arc and nitrogen 
lamps; the gates with their backing by G. E. lamps, the coach and 
portals by still more G. E.'s, about fourteen in all of these being used 
for this set. 

The nicety of light matching that was necessarj^ can easily be 
imagined. However, we had the good fortune to hght, test and 
photograph this entire scene in one night. 

The foregoing will give you a fair idea of the methods used in 
making these scenes. Of course, the chief consideration is that the 
scene be of dramatic value not in itself but as it will be used in the 
finished picture, in conjunction with the other scenes with which it 
completes an episode. Frequently, the best part of a miniature shot 
considered as an individual scene, is cut out because the dramatic 
action may be strengthened by the use of other scenes and all of this 
must be considered in the first planning of a trick shot. In fact, it is 
in this planning that a breadth of experience and knowledge counts. 
When it is once planned, all that is needed is care and artist r3^ Even 
when these scenes are finished and out of the hands of the man who 
makes them, they can be considerably enhanced in value by correct 
cutting and editing. Therefore, as far as possible, it is the miniature 
man's job to see that his work fits so perfectly the mood of the scene 
that it will be used as originally planned in the finished picture. 


Mr. Theiss: Is the half-exposure over the entire surface of the 
film or is it a split screen? 

. - Mr. Waller: That is over the whole thing; there was no split 
screen on any of that. 

Illusions in Cinematographij — Waller 71 

Dr. Hickman: What is the idea of making the horses go up hill 
at all if the camera can be tilted? 

Mr. Waller: That is a good question. There was, however, a 
good reason for it. We tried the horses on the level but it did not 
give the same effect because they showed no strain; the position of 
of the horses' bodies and the people on the coach made it look as 
though the picture had merely been tilted. We could steal on that 
by giving them a slight tilt. The horses strained on the traces a 
little and the people leaned forward a little. 

Mr. Jenkins: Were the portals built on .an angle? 

Mr. Waller: This much of the portals was not built; this (in- 
dicating) was. This was built at an angle to be perpendicular in the 
camera and all the glasses were plotted at this angle. 

Photographing Model Scenery. — Writers in the lay press and in 
journals of the tit-bit type delight in giving away what they believe 
to be the secrets of cinematography, and we often read of how railway 
accidents and other exciting events are photographed from well- 
made models. The idea, however, is by no means so new as many 
would have us believe it to be. In the 'sixties' of last century, when 
the stereoscopic craze was at its zenith, many interior views were 
obtained from models. Many of the once famous Ferrier and Soulier 
stereoscopic interiors were made from models, and their successors, 
Le\y et ses Fils, often built up a small model in order to make a 
stereoscopic negative of it when the picturing of the actual scene was 
impossible, and the work was so well done that few, if any, who 
purchased the pictures were aware of the deception. The models were, 
of course, made mainly from monocular photographs in order to 
picture the details as accurately as possible. A ''B. J." correspondent, 
who a generation or so ago worked in the famous stereoscopic studios 
at Grenelle, a suburb of Paris, assures us that the models were most 
realistic, much time and thought being expended in their production, 
the firm employing an expert scenic artist and model maker, one of 
whose masterpieces was an interior of the Coenaculum (Tomb of 
David), which may be in some of the collections treasured by ad- 
mirers of the stereoscope. (Brit. J. Phot. 1927, 74, 234). 


F. H. Richardson* 

SINCE the image upon the screen of the theater represents and is 
the finished product of the motion picture industry displayed 
for purchase by the amusement buying public, and since this is the 
only goods of any sort which the industry has for sale, it seems 
eminently fitting and proper that we spend a few moments in con- 
sideration of the faults most commonly found therein, and in exami- 
ning into the possibilities for at least their partial correction, if their 
complete elimination is deemed not practicable. 

That grave faults not only do exist, but also are very common, 
is apparent to those who view screen images with discriminating and 
understanding eyes. No one in the industry, I believe, seriously 
questions either their presence, or the fact that they operate to detract 
from the amusement value, and therefore from the sales value of the 
motion picture as represented by the box office income. 

If we concede the truth of the foregoing, then we cannot but 
agree that the reduction or elimination of screen image faults is an 
extremely important matter, no matter from what angle it be viewed, 
including the financial one. 

It is not the purpose of this paper to direct your attention to more 
than a few of the more serious faults. To consider them all in detail 
would serve no good purpose, since many of them are due directly to 
errors in projection procedure, few of which have any right place 
before this body. 

At the very head of the list of faults stands graininess of the 
screen image, which exists in widely varying amounts, from that 
barely sufficient to be visible, to an amount which has the general 
appearance of snow swirling and tumbling about in the air. Graininess 
is responsible for more real damage to beauty of the screen image 
than any other fault which can be named. 

To be able to fully grasp the evil effects of graininess it is 
necessary that one view scenes in which it is present, followed im- 
mediately by scenes in which it is not present, and through the 
kindly co-operation of the Universal Film Mfg. Co. which consented 
to prepare sufficient film for a demonstration before this body, I am 

* Moving Picture World, New York City. 


Some Faults — Richardson 73 

able to present to you a convincing illustration of the effect of 
graininess. Demonstration. 

The difference between film free from graininess and film con- 
taining it is, I think you will all agree, a bit startling. Graininess 
has the effect of changing the blacks to a more or less pronounced 
gray. The more delicate shadings in photography are either partly or 
wholly lost, because of the fact that the whites are no longer pure 
white, but have sufficient discoloration and density to very closely 
match the fighter photographic shades. 

One very bad effect of graininess is its tendency to blur the 
lines in the photograph, and thus set up the effect of lack of definition. 
In fact the effect of graininess is bad in every way. 

I am not a laboratory man and do not know^ the cause or causes 
of graininess. I have been told that much of it is caused by the duping 
of negatives in order to speed up positive printing. I have also been 
told this is not true. I have been informed that improper exposure 
of the negative in photography is responsible for much graininess. 
I have also been told this is not the fact. I am not a laboratory man, 
I repeat, and do not know what is the cause, but the effect I under- 
stand very well indeed, and it is distinctly bad. 

Interesting papers on the subject of graininess have been read 
before this Society in the past. One of them was by Arthur C. Hardy 
and Loyd A. Jones. It appears in the Teansactions (No. 14) of the 
Boston meeting held in the year 1922. 

Gentlemen, may I direct your attention to the fact that this 
paper appeared in the year 1922, yet five years later nothing effective 
has been accomplished in the reduction of graininess, notwithstanding 
the fact that it is now and always has been working literally tremen- 
dous damage in that it is rendering the placing of a perfect screen 
image before the public impossible. 

Some who should be in position to know assert that graininess is 
due to the use of .poor or unsuitable emulsion. What degree of 
correctness, if any, this statement carries I do not know. The cause 
and remedy is a matter for the attention of our laboratory engineers. 

In closing this matter I will say that graininess is present at least 
in some visible degree in at least some of the scenes of almost every 
production, and in all or practically all scenes of a very great number 
of them. 

74 Transactions of 8.M.P.E., JuUj 1927 

It is idle to say that graininess cannot be avoided. I venture the 
assertion that if all producers set a date some distance in the future of 
next year, beyond which time they would accept no positive print 
containing visible graininess, from that time forward, though pro- 
duction costs might be somewhat higher, there would be no more 
visible graininess. 

Another very serious and common fault is the lack of proper 
contrast values in the various portions of the screen image. Blacks 
are not blacks, but a more or less "dirty" gray. Blacks must be 
perfectly opaque and the various shadings of the photograph must 
have their true values if the highest possible value in beauty is to be 
attained in the screen image. 

There can be no possible argument on this point, yet it is a fact 
that we find an astonishing percentage of scenes in which there is no 
sharp, clear-cut values in photographic shadings, or in which the 
shadings have not their true values. 

This effect is because those portions of the film photograph 
which are presumed to produce black on the screen are not opaque. 
They "leak" light, hence the supposed-to-be black appears as a 
more or less pronounced gray on the screen. The contrast value is, 
of course, reduced, and if the light leakage be considerable, it is 
very greatly reduced. 

By the same process the various shadings lose their true values. 
They pass more light than they should, hence do not carry their 
correct proportions of contrast in the film image. 

The net result of this is two fold. First, as we have pointed out, 
there is no true contrast values, and the picture looks "flat." Second, 
there is an apparent damage to definition, though of course that is 
merely an illusion set up by lack of correct contrast and the effect 
of the hght leakage at the dividing lines between the whites and 
supposed-to-be blacks. 

Perhaps I have not described this condition as clearly as I might, 
but believe you have all viewed the effect so many, many times that 
you will understand fully just what I have in mind. However, again 
through the kindly co-operation of the Universal Film Mfg. Co., I am 
able to demonstrate the actual effect of the fault by contrasting it 
with an image which does not contain it. Demonstration. 
■ " The fault which perhaps stands third in ability to inflict damage 
to the screen image by detracting from its beauty is distortion, 
usually due to locating the projection room so high above the screen 

S 07716 Faults — Eicliardson 75 

that a projection angle varydng from considerable to very, very much 
in excess of the maximum projection angle approved by this body 
is produced. 

This fault is so very common and its evil effects so well under- 
stood, that there seems small need to discuss it. May I, however, 
venture to suggest the thought that in the past we, as a body, have 
made but very little effort to secure the actual adoption of the 
standards we have set up. 

A maximum projection angle of 12 degrees was approved by 
this body several years ago. Can we point to anything this Society 
itself has done to have this standard, or recommended practice 
adopted and put into actual general use? 

It seems to me we cannot reasonably expect to set up standards, 
or put forward recommendations for practice which are opposed to 
present methods, no matter how much in error present practice may 
be, and hope or expect them to be adopted unless we ourselves make 
at least a resonable effort to have them recognized and adopted. 

I would most respectfully suggest that when it is found that the 
industry is following a wrong and injurious practice, such as, for 
example, projection angles which produce hea\'y distortion of the 
screen image, and this Society, after due deliberation decides just 
what practice ought to be substituted therefor, and sets up that 
finding as a standard or as a recommended practice, it should go 
further and use every means available to it to secure the general 
adoption of the thing it has created. 

It would seem to me that this is of importance fully equal with 
that of the setting up of the standard or recommended practice 
itself, and that much might be done along these lines without imposing 
any undue hardship either upon the Society as a body, or upon its 
individual members. 

For example: Every one conversant with the facts knows that 
distortion of the screen image works to the detriment of the beauty 
of the picture, and hence operates at least to some extent to reduce box 
office income in theaters where it is present in objectionable degree. 

Exhibitors object to locating the projection room so that the 
projectors will be opposite the screen center, or nearly so, because of 
the fact that as theaters usually are now built, it would occupy 
space which might be used for other purposes, usually seating. The 
tendency is to place it way-back and high up, because up there 
space is least valuable of any in the entire theater. 

76 Transactions of S.M.P.E., Julij 1927 

Exhibitors do not as yet, save for notable exceptions, realize 
that the resultant damage to the beauty of the screen image set up 
by a heavy projection angle far more than counterbalances the 
presumed gain, because anything which detracts from the beauty 
of the picture works automatically and continuously against the box 
office. They overlook the fact that the gain in beauty of the un- 
distorted picture as against the heavily distorted one, will operate 
to make all the remaining seats a bit more saleable, and that thus 
the loss of even a relatively few of the most valuable seats will be 
even more than compensated for. 

Surely it would be entirely feasible for this body to have a 
carefully selected committee appear before both the exhibitor's 
and architect's organization, either in person or by written argument, 
and explain to them these matters in detail, urging that the standards 
and recommended practices of this body has set up be respected. 

Gentlemen, I most respectfully suggest that in future when any 
standard or recommended practice is set up by this body, in con- 
nection with the adoption of which by the industry it seems expedient 
to appoint such a committee or committees, that they be appointed 
by our President. 

I further suggest that a committee of suitable number, at the 
discretion of our President, be now appointed by him and instructed 
to appear before both the exhibitor's and architect's next convention 
in person if practicable, or if not then by written argument, and 
advise those distinguished bodies of the recommended practice 
this body has set up in the matter of projection angles, and the 
benefits to be derived from its general adoption. 

In closing I might say that if such a committee is appointed the 
fact should be stressed before the architect's body that in the past 
the theater has been planned with the projection room considered 
rather in the light of an unimportant necessary nuisance, instead 
of planning the room from whence the thing the theater will have 
for sale being planned first, and the theater built around it. 

True that may sound revolutionary, and even to some of you a 
bit absurd, but when we consider that a properly planned, properly 
located projection room is the only one from whence the screen 
image of highest possible sale value will or can reach the screen, we 
see that while it may be revolutionary insofar as has to do with the 
general present practice, it is in no sense absurd. 


J. I. Crabtree* 

WHEN a motion picture is viewed at a relatively short distance 
from the screen the various tones of the image are seen to 
consist of an agglomeration of small particles which appear to be in a 
state of boihng or scintillation. This lack of homogeneity of the 
tones of the picture is known as graininess, .and for a given image is 
more apparent the greater the degree of enlargement and the shorter 
the distance of the observer from the screen. 

The non-homogeneity of the image is due to the fact that a 
photographic emulsion is composed of small grains of silver halide 
which on development are changed to grains of metallic silver 
(see Fig. 1) . During manufacture the individual grains in the emulsion 
tend to congregate in clusters and the silver grains which are visible 
on the screen consist of such developed clusters. The individual 
grains of even the coarsest grained emulsions are too small to be 
visible on the screen. 

The apparent boihng effect is due to slight differences in position 
of the grain clusters as the single frame pictures are projected in 
rapid succession. 

The word graininess is apphed both to an undeveloped emulsion 
and the developed image. An emulsion may have inherent graini- 
ness due to the relatively large size of the grains and grain clusters, 
but the effect of this is only manifest in the developed image. Also, 
since the screen image is obtained by projection of a positive image 
which is usually prepared from a fine grained emulsion, it is of 
interest to study the extent to which the graininess of the negative 
image is recorded by the positive. 

Previous to the investigations of Jones and Deisch^ and Jones 
and Hardy ,2 little or no information was available regarding the 
factors which controlled the graininess of a developed image pro- 
duced from a given emulsion. Motion picture workers were aware 
that different scenes from the same roll of film often showed varying 
degrees of graininess for no apparent reason. It is now possible to 
explain why this occurs and to indicate some of the conditions which 
tend to reduce graininess to a minimum. 

* Research Laboratory, Eastman Kodak Company. 


78 Transactions of S.M.P.E., July 1927 

Factors Affecting Graininess During Exposure and Development. 

In their investigations Jones and Hardy^ measured the graininess 
of areas of uniform density obtained by varying the exposure and 
processing conditions. Their experiments were made by viewing a 
stationary image, and in most cases the author has confirmed their 
findings by preparing continuous lengths of motion picture film 
under practical working conditions and viewing the results on the 

It has been found that graininess is governed by the following 

1. The density of the silver deposit. 

Under any given conditions and with all emulsions the graininess 
of a silver deposit increases as the density increases up to a maximum 
at a density of about 0.3 and beyond this graininess decreases. This 
is as might be expected since a density of 0.3 transmits 50% of the 
incident light. If a series of parallel lines are ruled on a strip of film, 
on looking through the film the fines can be seen at the greatest 
distance when the width of the lines is equal to the space between. 
From this it is obvious that the various tones in the screen picture 
will exhibit varying degrees of graininess according to their density. 
Graininess is always most visible in the lighter tones such as the face 
and in a uniform area of relatively low density. It is possible there- 
fore to diminish graininess by avoiding large uniform areas whenever 
possible and when arranging a set by choosing backgrounds which 
will not render as densities around 0.3 in the final print. This 
however, is not a practical solution of the problem. 

2. The nature of the emulsion. 

In general, graininess tends to increase with the speed of the 
emulsion used but this is not an invariable rule because the inherent 
graininess of present day high speed emulsions is gradually being 
diminished by manufacturers without loss of speed. A perfectly 
grainless medium, however, whose sensitivity to light is of the same 
order as the present negative motion picture film has still to be made. 

There are many occasions when an extremely fine grained 
material such as positive motion picture film can be used successfully 
for making negatives such as sHde film negatives.^ Owing to the 
shorter latitude of this film in comparison with negative motion 

Graininess of M.P. Film — Crabtree 79 

picture film, the exposure must be more critical and a soft-working 
developer is necessar^^ to avoid excessive contrast. 

3. The exposure. 

The experiments of Jones and Hardy ^ indicated that for a given 
subject and a constant degree of development of both negative and 
positive, the graininess of the positive increased as the camera 
exposure of the negative was increased. However, projection tests 
with matched positive prints made from negatives exposed on the 
same subject at f/11 and f/3.5 and developed for the same time, 
showed little or no difference in graininess of the prints. 

The effect of exposure is dealt with at further length below. 

4. The time which elapses hetween exposure and development. 

If negative motion picture film with nitrate base is stored 
after exposure at relativelj^ high temperatures (80°F or higher) 
in the presence of moisture, there is a tendency for the latent image 
to fade, that is, after development the density of the various tones 
will be less than if the film was developed immediately after exposure.^ 

Experience has shown that negatives returned for deA^elopment 
by explorers invariably show excessive graininess whenever any 
considerable degree of fading of the latent image has occurred. 
The precise reason for this has not been investigated. 

It is ad\isable therefore to develop film as soon as possible 
after exposure, but if this is not practical the access of moist air to 
the film should be prevented because Httle or no fading occurs even 
at high temperatures in the absence of moisture. Precautions for 
handhng film after exposure in order to prevent fading in the latent 
image have been published b}^ the author.^ 

5. The nature of the developer. 

a. The composition of the developing solution. Jones and Hardy^ 
observed that Httle difference in graininess was produced by the 
developing solutions in common use. Repeated projection tests 
have shown that for all practical purposes this observation is true. 
J. G. Capstaff of this laboratory has recently found, however, that a 
developer with a high sulphite and low alkali content gives negatives 
of negligible graininess in comparison with that of negatives developed 
in the commonh^ used developers. The formula of this developer is 


Transactions of S.M.P.E., July 1927 

given later. Although this developer contains elon and hydroquinone 
as the reducing agents, other developing agents may be substituted 
without affecting its ability to produce fine-grained deposits. The 
borax merely functions as a weak alkali. 

The ability of the developer to produce fine-grained deposits 
is due undoubtedly to the solvent action of the sulphite on the 
silver halide emulsion. This not only reduces the size of each indi- 
vidual grain, but serves to prevent clustering or fusion during develop- 
ment of grains which are in close proximity to each other. The 

A B 

Fig. 1. Phomierographs of emulsion before and after deyelopment. 

reason for this is obvious from a study of Fig. 1. Fig. lA shows a 
cluster of silver hahde grains before development and Fig. IB the 
same grains after development. The fusion or overlapping of adjacent 
grains is clearly shown. Obviously, if the size of each grain is reduced 
during development by virtue of the solvent action of the sulphite 
the distance between the surfaces of two adjacent grains is increased 
and the possibility of fusion is reduced. 

The solvent action of the sulphite on the emulsion is revealed 
by the fact that the developer turns milky with use due to the 
presence of colloidal silver in suspension, while the walls of the 
developer tank become plated with metallic silver. Neither the 
presence of colloidal silver nor the plating out effect have any harmful 
effect on the developing solution. 

Graininess of M.P. Film — Crahtree 81 

Even with the higher speed emulsions, the graininess of negatives 
developed with this deA^eloper is of such a low order that it is necessary 
to stand quite close to the screen in order to detect any graininess 
in the picture whatsoever. 

Moreover, the improved sharpness of the positive picture 
resulting from the reduced graininess of the negative greatly improves 
its general photographic quality. 

h. Dilution of the developer. Jones and Hardy^ showed that 
contrary to popular belief, dilution of a developer tends to increase 
graininess slightly when developing to a given contrast. This is 
undoubtedly a result of the diminished solvent action of the sulphite 
on the silver grains which takes place to some extent in most develop- 
ing solutions.^ Dilution of the borax developer above has the effect 
of increasing graininess. It should be used in the concentration 

6. The degree of development. 

During development, at a constant temperature, contrast or 
gamma increases with time of development until a certain Kmit is 
reached. The contrast of the image at any moment compared with 
the Hmiting contrast which is possible in a measure of the degree of 
development at that instant. 

It has been shown experimentally that development of any 
particular grain of an exposed emulsion starts at a point or points 
within or on the surface of the grain, and as development proceeds 
these specks of silver grow until the whole grain is reduced to silver.^ 
It is obvious, therefore, that if development is arrested at an early 
stage, only relatively small silver particles remain after removing 
the residual unexposed emulsion in the fixing bath; whereas if 
development is carried nearer to completion the size of the developed 
silver grains is of the same order as that of the original grains. 

Since the visibility of the grains and grain clusters, which in 
turn determines graininess, is proportional to their size, it is apparent 
that a developed image of any given density obtained in one case 
by full exposure and low degree of development will in general be 
composed of smaller grains than one which received a short exposure 
and a full degree of development. 

Projection tests with flashed motion picture film obtained by 
varying the exposure and degree of development have confirmed this 


Transactions of 8M.P.E., July 1927 

In practice, however, the degree to which a negative is developed 
is governed largely by the brightness contrast of the subject. In 
the case of negative motion picture film the various scenes are 
developed for a sufficient length of time to produce a definite density 
contrast or difference in density between the highlights and shadows, 
although the particular density contrast to be taken as standard is a 
matter of personal choice. It is obvious, therefore, that negatives of 
standard density contrast with a minimum graininess can be pro- 
duced by employing contrasty lighting for the subject and developing 
to a low degree of development. 

In case the lighting of the object is not subject to control and 
if development must be forced, the borax developer will give a mini- 
mum of graininess. 































5 MiN. 10 MIN. 20 MIN. 

GAMMA 0.6 GAMMA 1.0 GAMMA 1.4 

Fig. 2. Showing arrangement of densities on a single frame of motion picture 
negative film for observing graininess on projection. 

If matched positive prints are made from negatives of the same 
subject developed to a low and high degree of contrast, respectively, 
within practical limits there is no difference in the graininess of 
the images. This is because low contrast development of the negative 
if offset by high contrast development of the positive. 

In order to confirm further the above conclusions, and to deter- 
mine the effect of printing through different negative densities, 
(obtained by varying the exposure and degree of development) 
on the graininess of a constant positive density obtained by a fixed 
degree of development, the following experiments were made. 

Strips of negative motion picture film were exposed on a motion 
picture printer with a series of neutral density strips fitted in the gate. 
These consisted of gelatin containing a black dye and were entirely 
grainless. The density strips were so adjusted that on developing 
the negative to gammas (degrees of development) of 0.6, 1.0, and 
1.4, respectively, the densities of the areas on each picture frame 

Graininess of M.P. Film — Crahtree 


measured 0.4, 0.8, 1.2, and 1.6, respectively. This was accomplished 
by trial and error. 

The negative frames after development appeared as in Fig. 2. 

Positive prints were then made from these negatives. These 
prints were all given the same degree of development and the ex- 
posure was so adjusted as to give a density of 0.4 from each density 







0.4 0.8 


FIG. 3. 

Fig. 3. Showing the variation of maximum graininess of the positive with in- 
crease in negative density (negative developed to different gammas). 

strip of the negative. Referring to Fig. 2 step A was printed to a 
density of 0.4, then step B was printed to the same density, and so on. 

The positive prints were then projected and the graininess of 
the various strips having a density of 0.4 were compared visually. 
Since the strips to be compared followed in rapid succession, a reliable 
comparison of graininess was possible. Three observers were em- 
ployed for judging the projected prints and they all concurred in their 
findings. The projection tests revealed the following facts: 

1. Maximum graininess of the positive appears in the tones 
having a density of about 0.4 to 0.5. This confirms the observations 
of Hardy and Jones. 

84 Transactions of S.M.P.E., July 1927 

2. Maximum graininess of the positive increases as the density 
of the negative increases from which it was printed. The increase 
is most rapid up to negative densities of around 0.8 and beyond this 
graininess increases only shghtly. The effect is shown by the curves 
in Fig. 3 which are merely relative. This means that other conditions 
being equal, an increase in exposure of the negative, which in turn 
increases the density of the various tones, tends to increase graininess. 
This confirm_s the findings of Hardy and Jones. 

3. In the case of a negative of given density contrast which 
has received a high degree of development, the maximum graininess 
of the positive print from this is greater than that of a similar print 
from a corresponding negative which received a low degree of 

With regard to the observation above that an increase of ex- 
posure from f/11 to f/3.5 did not materially affect graininess, this 
would appear to be in contradiction to the results indicated by the 
above curves. In practice, however, owing to the limiting contrast 
which it is possible to obtain by over-development of positive motion 
picture film, it is necessary to secure a certain critical density-con- 
trast in the negative in order to obtain a satisfactory positive print 
even with forced development. This density-contrast is of the order 
of 1.2, and assuming that the shadows have a density of 0.2, this 
means that a minimum highlight density of 1.4 is rec|uired in the 
negative. The above curves indicate that densities above this value 
do not give appreciably more graininess in the positive so that within 
a practical range of exposure, over-exposure of the negative has little 
effect on graininess. 

7. The conditions during drying. 
The experiments of Jones and Hardy^ indicated that abnormal 
conditions during drying, such as prolonged drying in a humid 
atmosphere at relatively high temperatures, did not affect graininess. 
It is possible, however, that under certain circumstances incipient 
reticulation may produce a condition resembling graininess. 

Graininess of Duplicates. 
An increasing number of prints from duplicate negatives are 
being exhibited in present day theaters. Such duplicate prints are 
often made from projection positive prints and their graininess is 
usually very objectionable. 

Graininess of M.P. Film — -Crahtree 85 

Up to within recent date it has not been possible to prepare 
satisfactory duphcate negatives with existing materials even when 
the original negative was available. If a negative is printed onto 
regular motion picture negative film so as to produce a master positive 
and in turn a duplicate negative is made from this, a print from the 
duplicate negative is objectionably grainy. This is a result of lack 
of resolving power of the emulsion used, or its inability to reproduce 
fine detail. During printing the emulsion is not able to record an 
image of the finest grains of the image being printed, so that each 
printing operation increases graininess. 

Motion picture film is now available which is especially adapted 
for making duplicate negatives. It consists of a fine grained emulsion 
containing a yellow dye and has greatly improved resolving power 
so that the increase of graininess produced at each printing operation 
is reduced to a minimum. Details for handling this film have been 
given by Capstaff and Seymour.'' Prints from duplicate negatives 
made on this material are only slightly more grainy than prints 
from the original negative, and providing the original negative was 
developed in the borax developer above, the graininess of the print 
from the duplicate is no greater than that of a print from a negative 
developed in an ordinary developer. 

It is obviously impossible to prepare a satisfactory duplicate 
negative from a regular projection positive print. DupHcates should 
always be made from the original negative whenever possible. The 
use of special duplicating film, however, will give the best possible 
results if only a projection positive is available. 

Practical Recommendations. 

Graininess in motion picture film can be reduced to a minimum 
by observing the following precautions. 

1. Forced development of the negative should be avoided 
whenever possible since graininess increases as the degree of develop- 
m.ent of the negative increases. In some cases the necessity of forcing 
development can be avoided by employing contrasty lighting when 
photographing the subject so that only a relatively low degree of 
development is necessary to produce a negative of average density 

This does not mean that negatives should be underdeveloped. 
If a negative of a flatly lighted subject is developed to a low degree 
of contrast it is necessary to force development of the positive, in 

86 Transactions of 8.M.P.E., July 1927 

which case the positive will be just as grainy as if development of the 
negative was forced in the first place. 

2. Develop ordinary and panchromatic motion picture negative 
film in the following developer which gives finer grained images 
than any other commercially used developer. 

Fine Grain Developer for Motion Picture Negative Film. 

Metric Avoir, 

Elon 2 grams 13 oz. 

Sodium sulphite (anhy. E. K. Co.) 100 " 41 lbs. 

Hydroquinone 5 " 2 " 

Borax 2 " 13 oz. 

Water to make 1 liter 50 gallons. 

Directions for Mixing: Owing to the high concentration of 
sulphite in this formula, it is somewhat difficult to dissolve all the 
chemicals unless directions are followed carefully. 

First dissolve the elon in a small volume of water (about 125°F) 
and add the solution to the tank. Then dissolve approximately one- 
quarter of the sulphite separately in hot water (about 160°F) and 
add the hydroquinone without stirring until completely dissolved. 
Add this solution to the tank. Then dissolve the remainder of the 
sulphite in hot water (about 160°F), add the borax, and when dissolved 
pour the entire solution into the tank and dilute to the required 
volume with cold water. 

With use, this developer may become slightly muddy but this 
is due to a suspension of colloidal silver which is likely to form 
and which is harmless and may be ignored. The tank usually becomes 
coated with a thin white deposit of silver but this does no harm. 

The development time varies with the number of feet which have 
been processed but the average time for a fresh bath is from 10 
to 15 minutes at 65°F. If a slower working developer is required 
the quantity of elon, hydroquinone and borax should be reduced. 
To obtain a faster working developer, increase the quantities of 
these chemicals. Dilution of the developer tends to destroy its 
ability to produce fine grained deposits. 

. * The life of the developer is practically the same as that of 
the usual motion picture developers in general use. An idea of 
the increase in development time with use may be gained from the 

Graininess of M.P. Film — Crahtree 87 

fact that after 4,000 feet of film have been processed per 50 gallons 
of developer the development time is practically doubled. 

The developer may be revived once or twice during its life 
by the addition of half the quantity of borax, elon, and hydroquinone 
originally used in the formula. A trace of sulphite should be added 
when mixing this reviving solution to prevent oxidation of the elon 
and hydroquinone. 

This developer is somewhat sensitive to the effect of sodium 
bromide produced by the conversion of the silver bromide in the 
processed film to metallic silver. A comparatively fresh solution 
is therefore necessary for developing extreme under-exposures. 
With average studio exposures, however, excellent negatives can be 
obtained even with the partially exhausted developer. 

3. When making duplicate negatives a minimum of graininess 
is insured by employing a special emulsion adapted for the purpose. 
Whenever possible duplicates should be made starting from the 
original negative and never from a projection positive unless this 
is the only record available. 

4. Keep the camera lens clean. A dirty lens scatters light, 
causing lens flare. This reduces the brilliancy of the negative in the 
same manner as slightly fogging the negative before development. 
In order to offset the effect of lens flare it is necessary to force develop- 
ment of the negative, which in turn increases graininess. 

^ L. A. Jones and N. Deisch, ''The Measurement of Graininess in Photo- 
graphic Deposits," J. Franklin Inst. 190, 657, (1920). 

2 A. C. Hardy and L. A. Jones, "Graininess in Motion Picture Negatives 
and Positives," Trans. S.M.P.E. No. 14, 107 (1922); see also monograph on 
"The Physics of the Developed Photographic Image" by F. E. Ross, Chapter II, 
p. 21, Van Nostrand, N. Y. 1924. 

3 R. Rogers, "Why SKde Fihn?" Trans. S.M.P.E., 10, No. 28, 230, (1926). 

^ J. I. Crabtree, "Handhng Motion Picture Film at High Temperatures," 
Trans. S.M.P.E., No. 19, 39, (1924). 

5 M. L. Dundon and J. I. Crabtree, "Investigations on Photographic 
Developers" Trans. S.M.P.E., No. 19, 35, (1924). 

^ E, P. Wightman, "The Inside of the Photographic Plate," Amer. Phot. 
329, June 1923. 

^ J. G. Capstaff and M. W. Seymour, "The DupHcation of Motion Picture 
Negatives" Trans. S.M.P.E., 10, No. 28, 223, (1926). 


Mr. Palmer : Mr. Richardson has called attention to the question 
that has come up here a number of times that the theaters persist 

88 ^ Transactions of S.M.P.E., July 1927 

in putting the projectors as high in the theater as they can get them. 
I want to suggest that the Secretary of the Society write a letter to 
Mr. Rothapfel of the Roxy theater expressing our appreciation of 
the fact that he has put his projectors in the center of the balcony 
of the theater. 

Mr. Crabtree: I should like to ask if anybody can tell me if 
duplicate negatives are shipped to foreign countries for making prints 
in order to eliminate the duties on prints made here. When news 
reels are sent to Canada are duplicate or original prints sent? 

Mr. Palmer: In the case of our own company we make two 
negatives, one for this country and one for abroad. 

Mr. Crabtree: How do you take care of so many contracts? 

Mr. Waller: The original negative is shipped to England and 
this negative is shipped to other countries later if there is need for it. 
In your contracts with releasing companies you have to promise 
your negative is free from dupes. The only exception is some scene 
that cannot be taken twice. About news reels I cannot tell you. 

Mr. R. C. Hubbard: I think I can answer Mr. Crabtree's 
question. They make one negative only and ship foreign prints from 
this country. 

Dr. Hickman: As Mr. Crabtree has dealt with this subject by a 
general survey of the field, perhaps he will forgive me if I answer 
Mr. Richardson on his behalf. In the application of the borax de- 
veloper graininess can be reduced to almost zero. Mr. Crabtree 
showed these films in Hollywood and they produced quite a sensation. 
A number tried the borax developer, but it will probably not be used 
for large scale production because eighty pounds of sodium sulphite 
are required for every tank. Although this quantity does not mean 
a large expense where the rates are cut to the smallest amount, it may 
make all the difference between profit or loss. Here is a remedy for 
Mr. Richardson's complaint, but the manufacturer has been doing 
all he can to cure graininess. The remedy will cost somebody a 
fraction of a cent more per foot. I think it is up to the publicity 
men, technical editors of newspapers who have the welfare of the 
industry at heart, to persuade those who do the processing of film 
not to use the cheapest solution but the one which will give the best 
results, even if the price has to be adjusted. 

. Mr. Griffin: I have two things I should like to say: One 
is an answer about the Roxy. While we have been recommending 
that the projection room be placed in line with the center of the screen, 

Graininess of M.P. Film — Crahtree 89 

it appears that having done that in the Roxy they have to some 
extent lost what they were after. The projection distance at the 
Roxy is approximately 110 ft. and in view of the fact that fairly 
short focal length lenses must be used it is generally conceded that 
the projection is not quite as good as it would be with longer focal 
length lenses. I think that we should go a little carefully about sug- 
gesting to architects the placing of the projection room in line with 
the center of the screen, particularly where extremely short throws 
would be the result. 

I should also like to bring to the attention of the Society the 
fact that Mr. Isaac and I were appointed by the American Projection 
Society to bring up the matter of film buckling. In the projection 
of pictures it has been found, and the complaint is very strong 
among the A.P.S. members, that film after projection buckles and it 
is impossible to get good definition. I should like discussion on this. 

Mr. Richardson: I cannot agree with Mr. Griffin. What he 
says is quite all right, but it doesn't in any way change the fact that 
we want the projection room placed on a level with the screen center. 
If Mr. Rothaphel had not turned this matter over to an architect 
who knew more about architecture than he did about projection, he 
would not have had that trouble. That room could have been placed 
in the right location without injury to anything. What we want is a 
compromise between the long and short projection distances and 
always an angle that will not give any appreciable distortion. 

Mr. Hill: I have not seen the projection at the Roxy Theater, 
and I don't know how it compared with that of longer focal length 
lenses, but there is no reason why we cannot have good projection 
with short focus lenses. I gave a demonstration in New York last 
summer with a two-inch anastigmat lens and everybody was well 
satisfied with it. When Lowe's want a theater, instead of giving the 
architect a blank piece of paper, they show him where the projector 
and screen are to be and tell him to build the theater around them. 
The projection outfit is first put on the paper by their projection 

With regard to buckled film, it is largely traceable to the reflector 
type of arc, and more especially to those which do not employ a 
condenser. The actual buckling of the film in the case of reflector 
arcs should not be greater than the buckling produced b^^ other 
illuminating units delivering the same heat at the film aperture, 
but in the case of the reflector arc, the in-and-out-of-focus effect 

90 Transactions of S.M.P.E., September, 1925 

produced by the buckling is much more noticeable upon the screen. 
Most of the reflector arcs have a condenser beam of very high 
relative aperature and as a consequence the projection lens is worked 
at full capacity which allows little or no tolerance in the focal plane. 
This results in noticeable want of focus on the screen even with 
very slight movement of the film at the aperture. Where the con- 
ventional condenser sj^stem is emploj^ed the objective lens is working 
at a much lower relative aperture since the smaller angle of the 
condenser beam produces almost identically the same effect as 
stopping down the projection lens with a diaphragm. The projection 
lens in this case has a consequently greater depth of focus, so that 
considerable warping or buckling vndjy occur without producing any 
noticeable effect on the screen image. 

Mr. Richardson: Replying to Mr. Griffin, the trouble is not so 
much with the lenses as it is with side distortion. When you come 
down to a three and a half inch lens or a four inch lens, the side 
distortion amounts to a lot. I believe short focus lenses can be made 
to give a perfectly good picture, but they can't take care of the side 

Mr. Jenkins: I have wondered many times why good quality 
prisms are not often used in front of the lenses in some houses to 
give perpendicular-to-screen projection. Let me give you a case: 
Here (indicating) are three machines, and only one is centered on 
the screen. I don't see why the projectors on the sides are not arranged 
at right angles to the middle one and fitted with prisms and the beam 
separated at the projection window only a few inches. That is onl}" a 

Going back to what I had first in mind: On occasions I have had 
too short a throw or too great an angle and have found it perfect- 
ly satisfactory to introduce a pair of mirrors. It does two things where 
you find lenses are not corrected as well in the short as in the long 
focus. For one thing you can always bring the main projected beam 
in the middle of the screen. You can also avoid putting the booth 
where it will cut off any seats or cut any seats out of the house. I have 
wondered why it is not done oftener. In Atlantic City in 1896 we 
had the problem of projecting a 6x8 picture, and the depth of pro- 
jection was only 12 feet, so we put the projecting machine behind the 
screen and projected towards the observers and into a mirror and 
turned it back on to the screen. Mirrors can be used; they don't 
have to be so large, and I wonder why they are not used oftener. 

Graininess of M.P. Film — Crahtree 91 

It can be done, and you don't have to rebuild the theater. You 
could correct the quality of the picture in many theaters already 

Mr. Griffin: I understand that while I was out, Mr. Hill 
stated that buckle was due to reflector lamps. I know that this 
happened in theaters where there are no such lamps in operation. It 
is due to improper drjdng of film before it reaches the presentation 
stage, and that is why it was brought up at this time. 

Mr. Coffman: May I take this opportunity to call attention to 
the crying need for authoritative literature on laboratory theory and 
technique? At present, there seems to be no completely authoritative 
information of this character available to the laboratory worker. 
There is even a tendency to throw a veil of myster^^ over the whole 
subject. Many laboratory superintendents, including some of the 
best, are men who learned their profession by rule of thumb, and 
their basic theoretical knowledge is quite limited. Prize formulas 
were acquired from friends who took them around dark corners and 
swore them to eternal secrecy before imparting the mystic proportions. 
And finally, by trial and error, most of them have arrived at very 
satisfactory technique. But this is certainly a very unsatisfactory 
condition of affairs, and only one phase of a larger problem which 
would seem worthy of the serious attention of the Society — that is, 
the need for the establishment of authoritative courses of instruction 
in the various branches of motion picture theory and technique by 
our recognized Educational Institutions. 

Mr. Powrie: I should like to refer back once more to graininess. 
Two years ago at Chicago I read a paper on the graininess in the 
projected image in which we made attempts to solve the problem by 
increasing the size of the negative film and reduce the image back 
to standard by optical projection. We have built a camera and have 
others in construction for the purpose of making a larger negative 
image and using an optical printer producing a far more perfect 
picture than we are able to get b}'' the ordinary method of contact 
printing. The cameras that are being built at present run the film 
in a horizontal position, and the film is only a little wider than stand- 
ard, 1-7/8 in., and gives an image four times the area. The question 
arises whether the increased amount of film would not be an objection 
but I truly believe that the question of cost is not so serious. Dr. 
Hickman suggested some alternative method of solving the problem 
and brought up the matter of cost. I do not think it is so much the 

92 Transactions of S.M.P.E., July 1927 

cost or a matter of increasing the size of the negative image and making 
the prints by projection. There is a good deal to say about making 
prints in an optical printer as against printing by contact. The camera 
being built for this purpose is called the "Magnigraph," and I think 
there is a great deal to be said on this point. 

New Hyper-sensitizing Process. — G. Seeber announces that a 
Japanese investigator has discovered a gas that can be used for this 
process, especially for cine film. It has been found that several 
gases act energetically on silver bromide, a few of them in a very 
short time, while others act so strongly that an accurate dose can 
not be administered. As is well known in the majority of cameras the 
length of film actually free from the magazines is comparatively 
short, but this is sufficient for the gas to get in its work. The great 
advantages of this method are first, that it is a dry method; the film 
is hyper-sensitized only just before exposure and there is no after 
fogging, as the film immediately leaves the gas zone. For commercial 
work it is suggested that a vent pipe may be fitted to the camera to 
allow excess gas to escape. Increased gas pressure as well as increased 
temperature gives greater sensitivity. It has not yet been determined 
how the gas acts, but provisionally it is assumed to be by catalysis. 
It is also said that a mixture of gases can be used as a color filter and 
that a color-sensitiveness is attained, such as has not yet been dreamed 
of. The gas may be dissolved in a liquid, as acetylene is in acetone, 
and a small bottle of 50 ccs. capacity, will suffice to sensitize 1200 
meters of normal film. Such a small container may be placed inside 
the camera, or in the tripod head. It has also been suggested that the 
legs of metal tripods might be filled with the dissolved gas. "The 
cameraman of the future will be in the position at any time not only to 
instantly increase at will the sensitiveness of the film, but also by 
simultaneous use of the gas to make it color-sensitive. This special 
possibility will work out in the most favorable way in taking films 
in natural colors." (Phot. Ind. 1927, 25, 329). 


V. A. Stewart* 

MAKE-UP for the Movies is a greatly misunderstood art. Un- 
fortunately the dramatic or speaking stage has had such an 
effect on the silent drama that nearly all of the artistes for the latter 
have been impregnated with wrong ideas as to the purpose of make- 

When our grandfathers went to the theater, footlighting was 
the means whereby the major part of the stage was illuminated, and 
the actors came as near as possible to the footlights, so as to render 
visible all the facial expression they were capable of presenting, and 
that when the actual sound of speech might require assistance, 
unconscious lip-reading would be of great aid to this end. 

Let us consider what was this source of light. In the early days 
candles were used; in Shakespeare's day reference is made to tallow 
dips for night entertainments, though performances were mostly 
given in daylight, as stage lighting at that time offered such in- 
surmountable difficulties. Oil lamps later supplanted the candles. 
About the year 1800 gas for illuminating purposes was being popular- 
ized, and it stood to reason that the stage soon fell into line for this 
style of illuminant, first with the open flame burners, then with the 
Argand burner (named after its inventor) and then, though somewhat 
sparingly used, came the Welsbach incandescent gas light. Gas was 
hailed as a wonderful advance as it permitted dimming or increasing 
the light at will. 

Around 1887 electric light made its presence felt — by the use of 
the Swan or the Edison carbon filament incandescent lamp. 

Particular attention is called to the yellowish color that was given 
by the forms of illumination referred to, so that make-up became a 
necessity, and colors were devised to offset this yellowness. The 
paucity of light of the early illuminants compared with that of modern 
theater lighting compelled the use of large quantities of artificial 
coloring of the crudest description. Whitewash off the walls, red 
bricks rubbed together to produce a fine powder, lampblack or 
charcoal from burnt matches, were still in use in my younger days, 
and, later, the red for the lips was obtained from the cork of a bottle 
of Uquid cochineal. 

* Fox Film Corporation. 


94 Transactions of S.M.P.E., July 1927 

It was about 1870 that certain German actors introduced grease 
paint which immediately became generally adopted. Even then, 
on account of the small volume of light on the stage, powder was not 
considered essential, and the horrible greasy effect of the paint after 
it had been exposed to the heat of the footlights passed unnoticed, 
or at least was not a subject of criticism. One colored grease paint 
was applied over another until the actor looked like an oil painting, 
crude when viewed closely, but, at a distance, appeared smooth, 
with the colors blending into a pleasing result. 

Making up used to take the old school of actors well over an hour 
before they were prepared to appear on the stage. The traditions 
then established anent make-up have been handed down to the 
present day, so that many of our actors are still making up for the 
old yellow lights although we now have Mazda and nitrogen-filled 
bulbs, spot-lights of single and twin carbon arcs, nitrogen Olivettes 
of high amperage, incandescent lamps, etc. Then, too, side lights and 
powerful overhead border lights are gradually causing footlights to 
be dispensed with. In spite of this greatly improved lighting no one, 
to the best of my knowledge, has tried to alter the make-ups to suit 
the new conditions. 

It is a fixed physical law that the power of a point-source of 
light diminishes inversely as the square of the distance from it, and 
when footlights are only a few feet away from the actor and the 
border lights behind the proscenium arch are perhaps 20 feet away, 
and assuming that equal candle power was given by each at its source, 
we would be getting only about one-tenth the effective illumination 
from the borders that we would be getting from the "foots." 

As is universally known, we are accustomed to seeing people on 
the street with the source of light coming from above them, causing 
all projecting parts of the face to cast a downward shadow. When 
footlights are used only a few feet from the actor the upward rays of 
light dispel the shadows to which we are so accustomed, so that 
artificial shadows have to replace the missing natural ones. 

Of course actors are not lighting engineers and have given no 
thought to this very important point, so it is up to someone to try 
and demonstrate the assistance which this very vital aid would give 
to their expression and art. 

As said before, all the old ideas of stage make-up have impreg- 
nated Motion Pictures of today. Those screen artists who were not 
originally stage actors have readily adopted the methods introduced 

Why is Make-up Compulsory — Stewart 95 

by their professional colleagues, with the awful results one sees on 
the screen every day, even among the stars. Their faces are so 
smeared with grease paint and light powder as to be almost inhuman 
in appearance. One genius thought he could improve conditions, and 
received some notoriety by the introduction of a yellow make-up. 
Quoting from a standard authority we read "the objections to yellow 
are that it is non-actinic, and, if the actor happens to step out of 
the rays of the arcs for a moment, or if he is shaded from the direct 
force of the light by another actor, his face photographs BLACK 
instantly." We are now speaking of ordinary or isochromatic film; 
panchromatic film will be referred to later. 

To give detailed instructions for making up for the screen would 
require a paper far too long and intricate to read before this meeting, 
so I shall touch briefly on the most important points : Why should a 
male actor make up as pale as a female on the screen? In actual life 
there is a considerable difference, so why not reproduce it on the 
screen? Why should an actor make up his face ludicrously pale and 
leave his hands their natural color, so that when he lights his cigarette 
his hands are like two black paws by comparison with his over-made- 
up face? Why are women permitted to rouge their lips with 
a yellowish-red lipstick which photographs jet black and looks like 
a shaped strip of black court plaster stuck on the lips? Why do women 
redden the points of their finger nails so that they photograph like 
dog talons? Why do actors when wearing ''sideburns" leave a space 
between their own hair and the artificially applied hirsute appendage? 
Why do they leave a big space between the inner ends of a screen 
moustache? So one could keep on — Why this? and Why that? 

All because such little common sense has been applied to this 
art — and it is an art, when thoroughly analyzed. 

Make-up should be as invisible as possible, so that a made-up 
motion picture actor by the slight addition of a little cheek rouge, 
should be able to go on the street without causing any comment. 

Make-up in motion picture work is for the purpose of doing 
away with the retouching of the negative that is customary with 
ordinary photography. Without make-up all the subcutaneous 
colorations due to the iron and red corpuscles in the blood, that are 
invisible to the human eye, are caught by the actinically sensitive 
emulsion of the photographic negative. 

I have taught several photographers a correct make-up for 
photography and they are so treating their subjects before taking 

96 Transactions of S.M.P.E., July 1927 

their pictures, thereby reducing the retouchers' art to a minimum. 
Most retouchers overdo their work so that the picture is generally 
altered into a vapid insipid face that one scarcely recognizes. It 
would be impossible to retouch a number of figures on a picture about 
the size of a postage stamp — one inch by three quarters of an inch — 
so that for motion picture photography, proper make-up becomes of 
paramount importance. To repeat, this statement is apphcable 
to the film now mostly in use. Many directors are trying to do away 
with make-up by using tinted incandescent bulbs and panchromatic 
film, but as this millennium has not yet been reached we must 
approach things as they are, and must prepare the face to do away 
with the necessity of retouching. Well and good. How to set about 
it would have been easy if we had not to unlearn so much that the 
speaking stage actors have instilled into their silent brothers and 
sisters, and, unfortunately, we can see on the streets many examples of 
flappers so made up that their faces look much like the actresses of 
old when only poor lighting was being used, as in the good old days 
of "East Lynne." 

Many books on make-up tell you that cold cream forms part of 
the make-up. Not so; cold cream is intended only for the purpose 
of cleansing the face so that the grease paint may be evenly apphed, 
but, in any event, every bit of this cream should be entirely removed 
before putting on the paint, otherwise the cream (which melts at 
body temperature) will affect the make-up. In the studio the greasy 
appearance of an actors' make-up is frequently very noticeable, but 
the director usually wants his people in a hurry and does not give 
them time to patch their make-up which may have been on for hours. 

This brings me to a point which I want to drive home: WHY 
use GREASE paints for motion picture make-up? 

There are several so-called "liquid" enamels, made of powdered 
chalk, oxide of zinc, rose water, a little glycerine, and some witch 
hazel, which have a covering power equal to, if not better than, 
grease paint, and which will not show as greasy an effect as one 
normally gets in a studio without any make-up. 

When I was still doing this class of work I had occasion to make 
up some Marimba Players, who were to be perched up near the top 
of a high set. I made them up with grease paint, and, after an hour 
or so of rehearsing, it was decided to shoot. I happened to catch sight 
o\ these gentlemen, and they were as shiny as well-oiled African 
slaves, and we had to hold the scene until they were patched up. 

Why is Make-up Compulsory — Stewart 97 

The next day I used what I call "Water Colors" by which I mean the 
enamel, and the only attention I had to give these men was to lightly 
powder them after lunch. This, and other experiences, caused me 
to abandon all cold creams and grease paints from my make-up box, 
and, since then, I have taught all my pupils only the water make-up 
method. I once made-up several j^oung ladies who were engaged at 
the Winter Garden, and, on the Saturday they had to hurr>" from the 
studio to be in time for their matinee. I added some rouge to their 
cheeks and with the enamel motion picture make-up they went on 
the stage that afternoon. I believe these girls, have all now adopted 
water make-up entirely in place of the grease paint to which they 
had become accustomed. 

This enamel has the power to cover all the blemishes and freckles 
which the flesh is heir to, and does not require the constant attention 
that grease paint does, and is far more easily removed at the end 
of the days' work. As a matter of fact, women need not remove it 
at all, but simply add a Kttle rouge to give a healthy color to their 
cheeks, which, of course, is absent in the picture make-up. Further- 
more, it does not soil men's collars or women's dresses. I hold no 
brief for any particular manufacturer, but attention should be called 
to the fact that there are several brands of liquid enamel on the 
market, some possessing the covering power that is so desirable, 
while others do not. The absence of the more expensive oxide of zinc 
is the cause of this. Prepared chalk is so much cheaper, and for 
ordinarj^ purposes is good enough, but for motion picture work it is 
not the eye we must satisfy but the photographic emulsion which 
must be primarily considered. The excessive use of grease paint is 
apt to cause immobihty of features, whereas enamel makes possible 
every movement of the face. 

One manufacturer made a lip-stick for me according to my 
formula which had a quantity of blue mixed with it. This had the 
effect of photographically lightening it, so that, though the actress 
might daub it on to her heart's content, the camera did not pick it 
up too strongly. All my powders had their content of blue. We have 
all noticed that when our ceilings are being calsimined the whitening 
has a large quantity of blue added to it. It is of a pale blue color when 
first applied, yet it dries perfectly white, free from halation that 
might otherwise be there — hence my use of blue in all my colors. 
The lips should be tinted with a small water color brush so as not 
to have any grease there — which is frequently transferred in the act 

98 Transactions of S.M.P.E., July 1927 

of kissing. Never should an actor allow any of the foundation to get 
into the orbit of the eye. The overeye should be shaded with lavender 
— a color which has a preponderance of blue over the red — and, if 
there happens to be any foundation color there, the lavender is 
adultered, and a mixed color is the result. Another thing: if grease 
paint be smeared all around and near to the eye it requires cold 
cream to remove it. All cold creams contain some preservative 
(generally sodium saHcylate) and this may get in the eye and cause 
what is frequently mistaken for "Klieg Ej^e." With the lighting used 
in studios, by means of hard and soft sources of illumination, we are 
practically reproducing daylight, yet in the dressing rooms of the 
actors there are some yellowish electric bulbs provided around the 
mirror in which the make-up is done. Generally one or two of the 
bulbs are in a direct line with the eye, so that the actor sees more of 
these lamps than he does of his own reflected image. Could anything 
be more ridiculous? The make-up may look perfectly good by the 
light in the dressing room, but absolutely bad when they walk into 
the lighted set. It is better that actors should make up by daylight 
when they are working in pictures. Even in this we see the old stage 
idea of making up by yellow light perpetuated, but though perfectly 
all right for the old stage make-up it is all wrong for pictures and 
modern stage lighting. In any event the position of the bulbs in 
relation to the eye is incorrect; the glare should be protected from 
the eye. 

When a male actor is adding hair to his face for some particular 
part he always tries to match the crepe hair to his own, overlooking 
the fact that dead hair photographs several shades darker than that 
on the living body. Glorious blondes imagine that they will screen 
so as to show off this beautiful shade, not knowing that the film 
records yellow as black — necessitating back lighting through the 
fluffiest of hair. Frequently this back lighting is so strong as to put 
the face in shadow. Camera men frequently blame the actor for a 
dark make-up when the excessive back lighting is really at fault. 

With ordinary film the slogan to be adopted should be: "Always 
err on the side of underdoing rather than applying too much make- 
up." When we come to color photography we must apply the same 
rule, but more latitude may be used, as we need some red on the 
cheeks, on each side of the septum of the nose, on the tips of the ears, 
and the inner corners of the eyes. In fact, all we need for natural 
color photography is a perfect street make-up. 

Why is Make-up Compulsory — Stewart 99 

Regarding the excessive make-up of some of our leading men, 
I have several stills in my possession of one of these gentlemen whose 
make-up was such that on development his face was the only one 
in the group — all the other people with properly made up faces being 
under-developed. If they had been brought out on the negative the 
leading man would have been over-developed or "burnt out." As 
the negative is always developed up to the star this inequality of 
make-ups is frequently seen. 

During my j^ears at the Vitagraph, Commodore Blackton was 
forever after me to check up on the amount of lip rouge used by the 
women, but it was useless — they won by wearing me out with my 
continual complaints. Wh.y directors and camera men do not control 
these things is one of the many shortcomings of this remarkably 
rapidly grown business. Some years ago I pointed this out to Mr. 
D. W. Griffith and he at once approved the idea and sent for the 
assistant director and instructed him to see that all make-ups conform 
to some sort of standard. How it worked out I never learned — but 
we all know the difficulty of trying to force principals into anything 
approaching system or order, though I met with a charming reversal 
of this rule with Miss Norma Talmadge. Her husband, Mr. Joe 
Schenck, asked me to consult with her on her make-up, and I found 
her a most receptive pupil. 

When I started to make a study of the art of make-up I secured 
certain paint makers' catalogues, showing the colors they manu- 
factured. These I had photographed in a hard light, a soft light, in 
dayhght, and under studio conditions, using special plates having 
the same numbered emulsion as the film being used. Every depart- 
ment (costume, upholstery, etc.) was supphed with copies as a guide 
for their colorations. Bj^ means of these photographed representations 
of all colors I was enabled to evolve the proper colors in my make-up 
for the emulsion then being used. 

Since writing the foregoing, there was published in the Liberty 
Magazine for April 9 an article entitled "How to Pass the Screen 
Test," by Brenda Ueland in which she saj^s "Be sparing of the lip 
rouge. Red photographs black. Don't try to change the shape of 
the lips by rouge. It always shows." Later she says "Discard the 
yellow grease paint myth that actors clung to for so many years. 
Nobody can explain it. There is absolutely no photographic theory 
to account for its use. Yellow is non-actinic, and if the actor is shaded 
for a moment from the direct force of the light, his face photographs 

100 Transactions of 8.M.P.E., July 1927 

black instantly." Further she says, "Don't come before the camera 
powdered a snow white. Some actresses think that the lighter they 
make themselves up the more youthful they will appear, whereas 
they only succeed in making themselves look like white billiard balls." 
Let us hope that though this article is printed in a non-theatrical 
paper, it will reach the eyes of the motion picture family, and have 
a good influence thereon. 

Though I have had no experience in make-up for Technicolor 
or other process of color photography panchromatic film, the first 
thing I would do would be to photograph the color catalogs under 
the new conditions and work accordingly. It should be quite a simple 
matter to get some 8X10 plates coated with panchromatic emulsion, 
and record the colors as before specified, and then evolve the proper 
make-up colors to be used. Face powders can be procured in any 
color, and by mixing them with the rose water solution, enamels can 
be made to give the desired result. The old joke about the ghastly 
appearance of motion picture actors may yet come true. 

Copies of previous issues of the Transactions that are still 
available may be obtained on application to the secretary, Mr. 
L. C. Porter, Fifth and Sussex Streets, Harrison, New Jersey. 

Nos. 1, 6, and 9 are out of print. The prices of the others are 
as follows: 

Nos. 2 to 8, $0.25 each; Nos. 10 to 15, $1.00 each; Nos. 16, 
17, 18, $2.00 each ; Nos. 19 to 28, $1.25 each. 

The supply of some issues is limited. 


Wilbur B. Rayton* 

THE lenses used for the projection of both lantern slides and 
motion pictures are unique in the realm of optical instruments 
in their apparent insusceptibility to marked improvement. Within 
the last fifty years no kind of lens or other optical instrument has 
failed to receive the meticulous scrutiny of experienced and ingenious 
designers with a result which is a record of more or less continuous 
improvement. In projection lenses, on the other hand, there are two 
standard types which, although one of them is almost as old as pho- 
tography and the other is beginning to assume an air of respectable 
old age, appear to meet the requirements of all kinds of projection 
in a fashion so satisfactory that noteworthy improvements have 
seemed to have been impossible. The records show not more than 
seven or eight patents granted on lenses said to be designed for pro- 
jection and many of these admit reduction of cost rather than im- 
proved performance to have been the principal object of the in- 

The two types of lenses referred to are the Petzval portrait lens 
and the triplet construction due to H. Dennis Taylor. The first was 
announced in 1840, the second in 1895. The general type of the first 
is shown in Fig. 1 and of the second in Fig. 2. It is of no interest 
here to record the details of construction of these lenses and in fact 
impossible, for probably every manufacturer uses formulae for his 
lenses peculiar to himself none of which are exactly like the original 
Petzval construction or like any of the originally published triplets 
of Taylor. Within a comparatively few years after its birth the 
original Petzval form was subjected to modification by Dallmeyer, 
Voigtlander, and Zincke-Sommer. These modifications have become 
classic lens forms but there have been scores of other modifications 
which have never been honored by special mention nor have they 
deserved it for they have not represented any sufficient degree of 
originality. Later in the paper reference will be made to some fairly 
recent lenses which at first glance appear to differ considerably from 
the Petzval form but which on closer inspection are seen to be closely 
related to it. 

* Scientific Bureau, Bausch and Lomb Optical Co. Rochester, N. Y. 



Transactions of 8.M.P.E., July 1927 

It appears to be pretty certain that the first commercial motion 
picture projectors sold in America were provided with Petzval lenses 
made by the Company with which the writer is now connected and 
the same type is now used almost universally for the projection of 
motion pictures and to some extent for the projection of lantern 
slides. For the latter form of projection, however, and for the pro- 
jection of opaque objects by means of reflected light, the triplet lens 



Fig. 1 — Petzval Portrait Objective. 

Fig. 2— Taylor Triplet. 

is better adapted and possibly less expensive. Of these three kinds 
of projection, the last is the most remote from the interests of motion 
picture engineers and, while interesting enough from the standpoint 
of the demands it makes on the projection lens, will not be discussed 
further here. 

The reasons why these two types of lenses are pre-eminently 
suited to these two respective kinds of projection are not difficult 
to find. Motion picture projection in the average house is a problem 
of projecting a picture which is small relative to the focal length of 
thB lens but which must be magnified to a degree which can reasonably 
be called enormous and yet with sharp definition and with all the 
brilliance of illumination possible. In respect of magnification of the 

Projection Lenses — Rayton 103 

image the projection lens is subjected to much more severe strain than 
the ordinary photographic lens. Consider the case in which we are 
projecting a film with a lens of 6 inch focal length and with a throw 
of 120 feet leading to a projected picture approximately 20 feet long. 
Viewed from the position of the projector the image on the screen 
would subtend exactly the same angle as the film would appear to 
subtend to an eye located 6 inches from it. Compared to the size of 
the picture as viewed from the projector, at 60 feet from the screen 
it would appear twice as large, at 20 feet six times as large. In other 
words at 20 feet from the screen the picture would look 6 times as 
large as would the film held 6 inches from the eye. A photograph 
on the other hand taken with a 6 inch lens would more likely be 
viewed at a distance of 12 inches or thereabouts so that, in comparison 
to the test to which an ordinary photographic objective is put, the 
projection lens in this hypothetical case is subjected to a strain no 
less than twelve times as severe. It is evident, therefore, that the lens 
which can successfully project motion pictures must have the finest 
definition possible. On the other hand the field of view which must 
be covered is much smaller than in ordinary photography. The long 
side of the film aperture subtends an angle somewhat less than 10 
degrees for a projection lens of 6 inch focal length while a photographic 
objective of the universal anastigmat type may be called upon to 
cover a field five times as great. 

In addition, however, to this requirement of extraordinarily fine 
definition there is the further requirement of high illuminating power. 
Now this property of the lens is gained by making its aperture large 
in comparison to its focal length within limitations which will be 
mentioned later. This practice, in all lens construction, leads to 
deterioration of definition because of the defect known as spherical 
zones. While it is generally possible to cause the light which, coming 
from any given object point, passes through the marginal zone of 
the lens to unite in the same image point as the rays which pass 
through the center of the lens, it is usually impossible to prevent 
the rays which pass through the intermediate zones from converging 
to points somewhat nearer the lens. The greater the aperture of the 
lens in comparison to the focal length the more troublesome becomes 
this defect. The two requirements of the lens needed for motion 
picture projection are therefore mutually antagonistic. They are 
met, however, to the most satisfactory degree by the Petzval type 
of lens which is characterized by its very excellent definition over a 

104 Transactions of S.M.P.E., July 1927 

small area even when the aperture of the lens is nearly half its focal 

In lantern slide projection on the other hand the magnification 
required is usually not more than a third of that required for motion 
picture projection and therefore the matter of high aperture is of 
relatively less importance. The field of view to be covered, however, 
is often larger. These requirements are better met by a lens of smaller 
relative aperture than the Petzval and one with considerably greater 
covering power, i.e., ability to form an image of satisfactory quality 
of a fairly extended object. Such a lens is the triple anastigmat. It 
performs excellently and is relatively inexpensive. It maj^ be of 
interest, however, to point out that lantern slide projection from a 
motion picture projection booth involves no greater angle of field 
of view than is required of the motion picture projection lens and 
such projection is often satisfactorily accomplished with a single 
achromatic lens or a telescope objective. 

Up to this point no reference has been made to the influence of 
the type of illumination employed upon the demands made upon 
the projection lens but the implication was made a few minutes ago 
that it might not always follow that increased illumination would 
be gained by increasing the relative aperture of the projection lens. 
In fact, in order to insure that an increase in the relative aperture of 
the projection lens shall be effective, it is necessar>^ to see that the 
aperture of the illuminating system be sufficiently large. 

In order to pursue this matter a little further it will be convenient 
to introduce the expression "angular aperture." If an eye be placed 
at the center of the film gate and turned towards the objective, the 
largest circle of light visible subtends at the eye an angle which we 
call the angular aperture of the objective. Similar 1}% if the eye turns 
towards the illuminating system the largest circle of light seen sub- 
tends at the eye an angle which is the angular aperture of the illumi- 
nating system. Now, in so far as the central point of the film gate 
is concerned, there is no gain in illumination if the angular aperture 
of the projection lens is increased to a value greater than the angular 
aperture of the illuminating system. Now, the angular aperture of 
the illuminating system is a complex thing. In addition to the physical 
dimensions of the optical units of which it is composed it depends 
upon the size of the light source and upon the location of the image 
of the light source with respect to the film gate. The illustration in 
Fig. 3 will help to illustrate this point. Here a motion picture pro- 

Projection Lenses — Ray ton 


jection system has been reduced to its lowest terms, the source of 
Kght, the condenser, the fihn gate and the objective. The sohd lines 
limit the pencil of light which, originating in the central point of the 
light source, is converged by the condensing lens into an image in 
the plane of the objective. The dotted lines intersecting in the center 
of the film gate at the point P' measure the angular aperture of the 
illuminating system only under the condition that the source be large 
enough to fill the dotted cone extending to the left from the condenser 
to the point P which is the image formed b}^ the condenser of the 
point P\ The illustration shows the source just large enough to 





Fig. 3 — Schematic Motion Picture Projection System. 






Fig. 4 — Projection Objective with Short Back Focus. 

meet this condition. If the light source were smaller than shown in 
this sketch it would be impossible for the condenser to appear filled 
with hght when viewed from the point P' . This follows from the 
fact that no ray of light leaving any point of the light source other 
than the extreme margin can pass through the margin of the con- 
denser and also through P' . The figure also shows that the angular 
aperture of the objective is larger than that of the illuminating 
system since the dotted lines do not reach to the margin of the lens. 
No light, therefore, reaches the marginal zone and the excess diameter 
is useless in so far as the center of the field, at least, is concerned. 
For the same light source the angular aperture of the illuminating 
system can be increased or decreased b\^ altering any one of several 
dimensions of the system but consideration of these points would lead 

106 Transactions of S.M.P.E., July 1927 

us into a field too remote from the subject of this paper to justify it. 

After meeting to the best possible advantage all the conditions 
which must be imposed upon an illuminating system for motion 
picture projection, the ordinary condenser type has an angular 
aperture of about 20 degrees when adjusted to best advantage for a 
projection lens of 6 inch focal length. The reflector arc has a higher 
angular aperture. The most popular type reaches a value of 27 

Now it has been frequently observed that some projection lenses 
which present a very satisfactory image with condenser illumination 
do not perform so well when used with a reflector arc. This is certainly 
possible if the angular aperture of the objective is larger than that 
of the condenser illuminating system. Under this condition less than 
the full aperture of the objective is used for the imagery of any given 
point of the film when condensers are used whereas more of the 
aperture or the full aperture would be used when the change was 
made to the reflector arc. Because of the spherical zones in the 
projection lens, which are always present to a greater or less degree, 
or because of deliberate over-correction of spherical aberration the 
lens might fail to give satisfactory projection with a reflector arc 
even though its performance with condensers was entirely satis- 
factory. It would be more or less accidental if a lens designed for 
condenser illumination happened to be at the same time adjusted 
to the best condition for reflector arcs. If reflector arcs are to be 
used with their full efficiency they require projection lenses which 
are designed to give the best possible image with very high relative 

In spite of all its merits, the Petzval lens cannot be absolutely 
corrected simultaneously for astigmatism and flatness of field even 
for the small angular fields of view involved in the average motion 
picture projection. The margin of the field is, therefore, never as 
well defined as the center. This defect escapes the notice of the 
average patron of the theaters because the action is generally con- 
centrated within the central two-thirds or less of the picture area and 
the material which fills up the margin does little more than constitute 
a frame for the interesting part of the picture. It is natural to inquire, 
however, why an anastigmat construction such as is used in pho- 
tography would not offer better projection. The answer is that while 
the anastigmat produces well defined pictures of much greater angular 
extent than is required of a projection lens, it does it only at relative 

Projection Lenses — Rayton 107 

apertures which are less than those required in projection objectives. 
If an anastigmat be increased in diameter to give the relative aper- 
tures required of motion picture objectives the increase in spherical 
zones becomes so great that there is very perceptible deterioration 
of definition in the very center of the picture. The Petzval con- 
struction is characterized by small spherical zones and for this reason 
has been the favorite lens for the projection of motion pictures since 
the beginning of the art. 

There has developed recently, however, a desire to reduce the 
projection distance below the previous average value without cor- 
respondingly decreasing the size of the projected picture. This will 
lead either to pictures whose margins are very poorly defined or else 
to the adoption of an anastigmat lens. If the latter expedient be 
resorted to, either the relative aperture of the lens must be decreased 
or less sharp definition be accepted over the whole area of the picture 
than is now expected. If the relative aperture be reduced in the 
interest of definition then illumination must suffer unless light sources 
of very high intensity become available. Another difficulty may be 
presented in the increased difficulty of getting an appearance of even 
illumination because of the greater angle of incidence on the screen 
of the pencils of light forming the marginal image. It is very doubtful 
whether the advantages which follow from the use of the very short 
projection distance are not overbalanced by the disadvantages in 
the quality of the projected picture. 

In the early part of the paper it was promised that reference 
would be made later to some recent lenses which differ from the 
Petzval type of lens. Two patents have been issued which describe 
lenses very similar to each other, one of which claims decreased cost 
of production and the other increased illumination. These lenses, 
both of which are on the market, differ from the Petzval construction 
in that the back component is relatively close to the film gate. It may 
be argued, however, that the difference in construction between 
these lenses and the Petzval is more apparent than real. Referring 
again to Fig. 1, the front component is seen to resemble very much 
a telescope objective. As a photographic or projection objective, 
a telescope objective would be unsatisfactory because of its very 
Hmited field of sharp definition and because of its insufficient relative 
aperture. By adding to the telescope objective a second component, 
however, the combined focal length can be very much decreased 
thereby gaining the necessary speed and, further, by a suitable choice 

108 Transactions of S.M.P.E., July 1927 

of shapes and glasses of the lenses of the rear component and its 
distance from the front lens, the useful field of view can be extended. 
Such, in fact, may be said to be the principle of construction of the 
Petzval lens. The front component differs somewhat but not greatly 
from a telescope objective; the back component adds to the light 
gathering power and to the field of view. Viewed in this light, the 
new lenses the type of which is represented in Fig. 4 do not differ 
greatly from the Petzval. From the standpoint of performance, 
nothing is claimed for the one while for the other it is claimed that it 
leads to a brighter image. This can be true, however, only if it can 
be shown that the construction makes it possible to produce lenses 
of higher relative aperture than other types and that the angular 
aperture of the illuminating sj^stem is large enough to make use of 
the enlarged aperture of the projection lens. Otherwise the mere 
fact of making the back focus short or, in other words, of bringing 
one of the components close to the film gate cannot have any effect 
on brightness of image. 


Mr. Townsend: As I understand Mr. Raj^on, this latter type 
of lens theoretically does not give more light, but most projectionists 
will say that it does give considerably more so as to be perceptible 
to the eye. I wonder how that could be explained. 

Mr. Rayton: In photometric comparisons of these lenses, all 
of which were reduced to the same relative aperture, we found no 
difference. A slight difference will exist in the case of a lens whose 
back component is cemented as compared with one whose back 
component is not cemented because of loss of light at the uncemented 
surfaces. When the lenses are diaphragmed to the same relative 
aperture, there is no other difference. 

Mr. Egeler: With the objective and 16 mm. film the projection 
distance is often a quarter or a fifth that of the 35 mm. film. Should 
it not be possible to use certain types of construction for the smaller 
film which would allow the large aperture because the ratio in film 
width is 2: 1 whereas projection distance would of the ratio of 4: 1 or 
figures of that order? 

Mr. Rayton: As a rule, the angular field in projecting the half 
size film is at least as great as in ordinary theater projection of full 
size film. While special lens constructions may be in use in amateur 
work, I was not thinking of that type of projection. 


Frank Bexford* and M. W. Palmer** 


The reasons that make it desirable for the motion picture studio to employ 
large floodhghting units are the high levels of illumination required for high 
speed photography and the pecuHar sensiti\dty characteristic of the photographic 
film. These two factors indicate the use of a high intensity arc, and there is a 
national tendency to take the high intensity searchhght just as it has been devel- 
oped for military service and by refocusing get a beam of wide spread. The defects 
of this method are illustrated and it is shown that a more suitable optical arrange- 
ment is to use a polygonal mirror rather than a paraboloid. The method of comput- 
ing the dimensions of the polygons is given along with data on a photometric 
comparison of the two types of reflectors. 

Studio Use of High Power Floodlights. 

THE intensity of illumination required for the taking of motion 
pictures is of the general order of one hundred times the illu- 
mination under which ^Ye may comfortably work and read in our 
offices and homes, and the motion picture art requires much special 
lighting equipment to attain these high intensities. There is a further 
difference between the every day use of artificial illuminants and studio 
practice, and that is the obvious fact that in the office or home we 
are interested in the reaction of the eye, but in the studio we are 
interested in the reaction of the photographic film. The film centers 
its reaction on the violet and ultra-violet regions of the spectrum, 
and as a result the brightness of illumination as measured by the eye 
with the aid of a photometer is not a reliable measure of the photo- 
graphic intensity. One of the outstanding results of this difference is 
the use in studios of several light sources, the high intensity arc 
among them, that are not commonly considered as illuminants for 
floodlighting purposes. 

The high intensity arc is essentially a high current arc and 
this fact alone leads to a few large units rather than a number of 
small ones, and the unique demands here made call for a type of 
unit that is not essential in any other phase of the illuminating art. 

As motion picture sets have become increasingly larger, it has 
become more and more necessar}^ to use high intensity sources with 

* Physicist, Illuminating Engineering Laboratory, General Electric Company. 
** Electrical Engineer, Famous Players-Lasky Corporation. 


110 Transactions of S.M.P.E., July 1927 

some means of carrying the light from this source into the set. 
The prevaihng method, up to this time, has been to use parabohc 
mirrors of 24 and 36 inch diameter, with a 150 ampere arc. These 
mirrors are very expensive, heavy, and easily breakable; a mirror 
frequently breaks in the first week of use. Consequently, the studios 
have welcomed this polygonal mirror from the economic, as well as 
the practical angle. 

Floodlight Beam from Parabolic Mirror. 

A floodlight beam from a parabolic mirror has certain peculiari- 
ties that seriously interfere with its usefulness as a source of general 
illumination. On the other hand it has certain excellent features and 
it has been successfully used in many studios. The mirror is usually 
mounted in a barrel to support it and to cut off the radiation of arc 
light to the sides and rear. This barrel enters into the optics of the 
beam and in every case where the barrel is of normal proportions it 
leads to a loss of light as can be illustrated by the aid of Figs. 1 and 2. 

If the arc is moved from the focal point along the axis of pro- 
jection so as to increase its distance from the mirror the beam may 
be made to converge to any desired degree. After the beam passes 
through the point of convergence it becomes divergent and spreads 
to the desired width. This bteam when formed by the use of a search- 
light mirror of the precision type has great smoothness of texture, 
being generally free from images or dark spots, but there are two fea- 
tures about it that must be ranked as defects of the first order. The 
edges of the beam are much brighter than the central- parts. This 
change in brightness is gradual and therefore often not strikingly 
apparent to the eye, but it nevertheless reduces the effectiveness of 
the central parts and wastes light around the edges where it is not 
useful. The second defect is the presence of a dark spot or shadow 
of the lamp mechanism that appears in the exact center and along 
a radial zone to the upper edge of the beam. This is illustrated in Fig. 
3 where the curve and sketches are from physical measurements made 
on an experimental floodlight beam. This mechanism shadow can 
be reduced in harmfulness but not entirely eliminated by moving 
the heads several inches below the axis. This moves the spot towards 
the top of the beam, but does not entirely remove it from the field. 
In Fig. 7, curve A, the distribution is seen to be unsuitable for general 
floQdhghting, although in the particular floodhght of which this is an 
actual test, the lamp was lowered several inches in order to avoid the 
central dark spot. 

Polygonal Floodlight Mirror — Benford and Palmer 111 

The convergent form of the beam is also accompanied by the 
secondary effects as follows: 

(1) An abnormal loss of light due to the convergent beam falling 
on the mechanism of the lamps heads ; 

(2) An overheating of the front door that is occasionally used. 
In cases of extreme convergence the glass may be heated nearly to the 
melting point, with a severe loss in clearness and transmission; 



FIG. 2 

Fig. 1 — Optical sketch of light source placed to give a convergent beam from a 
paraboloid. This arrangement does not involve a loss of light on the inside of 
the barrel, but the interference of the head mechanism may be serious. 

Fig. 2 — Optical sketch of light source placed to give a divergent beam. There 
is here considerable interference by the barrel. The lamp heads may be 
lowered to throw the lamp shadow towards the outer part of the beam. 

(3) A decrease in the amount of light incident upon the mirror. 

The alternative plan is to move the lamp closer to the mirror. 
This, in general, produces the same results as before, with certain 
variations that are easily recognized. There is a loss of light in the 
beam because the extra Hght that falls upon the mirror is reflected 
onto the inside of the barrel, and even some of the light that is ordi- 
narily useful is lost in the same way. In the typical case illustrated 
in Figs. 1 and 2 the parallel beam being made equal to 100, the 
convergent beam as it leaves the effective part of the mirror is 90, 
and the divergent beam is 72. In a particular design to be noted later 
the barrel loss was about twice as great as in this example. Thus 


Transactions of 8.M.P.E., July 1927 

any refocusing of the lamp either towards or away from the mirror 
leads to a loss of beam flux, and the wider the beam is made the more 
serious does this loss become. 

The distribution of light in the initially divergent beam is very 
bad. See the two left hand sketches of Fig. 3. A bright ring of high 








' \ 



\ n 





') ^ 





















/ 12 13 14 IS 1(3 11 IS 

Fig. 3 — A photometric exploration for beam outline and width when using a 
paraboloid and a high intensity are adjusted along the optical axis. 

intensity encircles the beam, and inside this the intensities fall off 
to low values. The shadow of the lamp mechanism is not so sharply 
outlined as before, but it still must be moved from the center or 
otherwise avoided. 

The Polygonal Mirror. 
, During the last few years a considerable amount of attention has 
been given to the theory and performance of a type of mirror known 
as the sectional or polygonal mirror. This mirror is made of a metal 

Folygonal Floodlight Mirror — Benford and Palmer 113 

back spun to a parabolic form, and lined on its concave side by numer- 
ous pieces of flat mirror glass. It has been demonstrated* both 
mathematically and by actual test that if certain proportions are 
observed in forming the individual mirrors the resultant beam will be 
free from images and highly uniform in intensity in its central part. 
The basic equation of such a mirror is : 

a ^ a 

la-\-So COS^ COS a = pa slu (Z + ^o COS 

2 2 


la is the angular length of a section, measured along a radial 
centerline ; 

Pa is the angular width of a section, or 360 divided by the number 
of mirrors in the zone; 

So is the angular diameter of the light source measured from the 
vertex of the complete mirror ; 

a is the angle, measured from the axis to the center of the 
particular section being designed. 

When the conditions of this equation are fulfilled each mirror 
will give a beam that coincides in direction and in average size with 
all the other individual beams. With all beams covering the same 
field it is self evident that the action of any one particular section is 
not of vital importance. Several trial mirrors were built with a com- 
mercial grade of rolled glass mirrors, but it was found that the 
imperfections in the glass set up zones or images in the beam. These 
images were not of great strength or of much visual prominence, 
but they rendered the beam defective, particularly if it was moved 
during the taking of a scene. Later, mirrors of plate glass were used, 
and they gave a beam almost wholly free from this defect. Only the 
outer zones of the beam show traces of the individual beams . 

In Fig. 4 is illustrated a front view of a 36 inch diameter mirror 
designed to give a beam 30 degrees in diameter. There are three 
zones of mirrors. The central zone contains four sections, the inter- 
mediate zone nine, and the outer zone twelve sections. The beam 
from each section has a general resemblance in outline to the form of 
the sections in the diagram. The sections are here seen in perspective 
and are foreshortened somewhat, which has the effect of making them 
appear more nearly equal in length and breadth than they actually 

* Benford, "Studies in the Projection of Light," General Electric Review 
Dec, 1925, and March, 192o. 


Transactions of S.M.P.E., July 1927 

are. The optical relation of the image back of each section to the 
outline of that section carries this foreshortening still further and 
the individual beam becomes more nearly equal in the two diameters 
corresponding to the two centerlines of the section of mirror. As 


Fig. 4 — A typical form taken by a paraboloidal shell "when lined with polygons 
designed to give individual beams of uniform sectional area. 

an illustration, the average width of a mirror in the outer zone is 
7.81 in. and the length is 8.50 in., but the beam from this mirror is 
almost square in section, and each of these square beams is rotated 
30 deg. from the orientation of the beam from an adjacent mirror 
in the same zone. As a result of the way in which the corners of the 
beams are spaced around the edge of the combined beam they are 
almost wholly lost to view, and the beam appears circular in outline 
with a series of 48 faint scallops equally spaced around the edge. The 

Polygonal Floodlight Mirror — Benford and Palmer 115 

beam from all twenty-five sections has twenty-five individual beams 
with over one hundred scallops and the multiple form of the beam 
is visible only around the extreme edges and not at all in the center. 
This 25 section mirror gives 25 indi^ddual beams from the 25 
images that are back of the mirrors, and an opaque object in the beam 
therefore casts 25 shadows. This feature has been given some study 

Fig. 5 — A study of the shadows formed by a polygonal mirror. There is a 
separate shadow for each section of the polygon, 16 in tliis particular case. 

because it was once thought that this compound shadow might be 
objectionable. It has since been found that in studio practice this 
form of shadow is to be preferred to the sharp and clear shadow from 
a parabolic mirror. There may, of course, be exceptional cases where 
the sharp shadows are to be preferred, and therefore data on the sub- 
ject is of importance. 

In taking the shadow photograph of Fig. 5 the five subjects were 
arranged as follows. The man on the left was 5 feet from the white 
screen. The others were spaced back at 5 foot intervals so that the 
man on the right was 25 feet from the screen. The floodlight itself 
was 60 feet away on a line normal to the center. The progressive 
separation of individual shadows produces a peculiar type of com- 

116 Transactions of S.M.P.E., July 1927 

posite shadow but in the presence of other hght the composite shadow 
loses much of its "cubist" tone and becomes merely soft-edged and 

If the harsh shadows of direct sunlight are desired in portraiture 
this beam will give the desired results. To illustrate this a "close up" 
was taken with the sitter at 25 feet from the mirror. The photograph 
of Fig. 6 shows clear and distinct shadows and there is but little 
evidence of the multiple character of the beam. 

Test Data. 

Among the tests that have been made with the polygonal mirror 
there is one that is of direct interest to the Society of Motion Picture 
Engineers, and the data of this test will be given in preference to 
several other tests that were more elaborate and of higher accuracy. 
This test was made at the Famous Players-Lasky Studio, and certain 
features of the test therefore are a faithful duplication of studio prac- 

A 150 ampere arc was focused (on the axis) to give the designed 
spread of 30 deg. It w^as found that, due to mechanical limitations, 
the arc could not be brought closer than 12.75 in. to the mirror, where- 
as the designed operating focal length was 12.20 in. The effect on the 
beam was not great because the arc is not sensitive to focal ad- 
justment and to produce a sensible change in beam formation the 
lamp must be moved through several inches. 

The beam was directed against a wall one hundred feet away 
with the center of the beam 5 feet above floor level. Reading stations 
were marked off at 5 foot intervals for the width of the beam, and 
photometer readings were taken at each, making two complete 
traverses of the beam. Constant current of 150 amperes was held in 
this and in the test that followed. 

The measured beam formation is given by curve B of Fig. 7. 
This curve shows a central zone 15 degrees wide over which the beam 
is substantially uniform in intensity and an annular zone 7 degrees 
wide of gradually decreasing intensity. The width of this outer zone 
is abnormally wide due to interference by the lamp barrel with the 
light from the outer zone of the mirrors. With a barrel designed to 
conform to the beam dimension the beam will have the form of 
curve A, Fig. 8, which is a computed curve. The central zone of uni- 
form intensity is nearly 20 degrees wide, and the whole width is 32 
deg. Curve B of this Figure is the computed beam, taking account of 

Polygonal FloodJiglif Mirror — Benford and Palmer 


the loss of light through the interference of the barrel, and curve C 
is the form of characteristic obtained by actual test. The disagree- 

FiG. 6 — A studv of face 

shadows from a 15 section polygonal mirror at 25 
feet distance. 

ment between the two is probably due to the fact that only six read- 
ings were taken at each point in the beam. 

The quantit}^ of light in the full beam is computed to be 322,000 
lumens, and the barrel interference reduces this to 254,000 lumens. 
This light includes the orange light of the flame, and the floodhght 


Transactions of S.M.P.E., July 1927 

beam is noticeably whiter than the searchHght beam produced by 
the same arc. This color difference arises, of course, from the flame 
light being outside of the true searchlight beam and hence lost for 
projection purposes. 


B- POLYGONAL Z54W0 31 ° 



' — 












1 Q-' 



























P 14 12 10 3 G ^ Z Z 4 G 3 10 IZ 14 k 

Fig. 7 — Beam characteristics of a 150 ampere arc with A — 36 in. dia. parabo- 
loidal mirror ; B — 36 in. dia. 25 section polygonal mirror. 

Under the same conditions of test the parabolic mirror gave 
a characteristic distribution as shown by curve A, Fig. 7. The central 
dark spot is still strongly evident despite the fact that the lamp was 
lowered several inches below the axis. The ring of high intensity 
around the edge of the beam is highly characteristic of this type of 
mirror, and the wider the beam is spread the more pronounced will 
this maximum become. 

. ' It may not be out of place to remark that the sectional mirror 
is, next to the plane mirror, the oldest type known. The Roman fleet 

Polygonal Floodlight Mirror — Benford and Palmer 119 

at the siege of Syracuse is supposed to have been set on fire by sun- 
hght reflected from a mirror built by Archimedes. Regardless of the 
accuracy of this account, the sectional mirror has been used on 






(O 3.000 

% zpoo 

^ 1500 


1 1000 


S 500 




1 1 1 1 1 1 1 1 1 1 ' M 1 1 1 1 

A BP 522.000 - 



B Z9° ES4,O0O 




C 50° E 54.0 00 







































^ y 











') 5 /O 15 ^0 ai 


Fig. 8 — A study of the effects of barrel interference with the beam from a 
polygonal mirror: A — Unobstructed beam; B — Obstructed beam (computed); 

C — Obstructed beam (test). 

various occasions, particularly in theatrical work, and therefore the 
basic conception of a sectional or polygonal mirror is not a matter of 
current history. The new feature of the present mirror is the manner 
in which the individual mirrors are formed so as to give a multiplicity 
of beams, each agreeing as far as possible with all the other beams 
both in direction and in size. 

120 Transactions of SM.P.E.,- July 1927 

Among the obvious advantages of this type of mirror are: 
cost, ease of repair, lessening of damage when overheated, greater 
economy of hght projection, and a superior type of distribution of the 
hght in the beam. 


Mr. Porter: The type of reflector described is that designed 
for the relatively highly concentrated source of the arc; has Mr. 
Benford used a 10-kilowatt Mazda lamp? 

Mr. Benford: In designing this mirror, if you want to do a 
nice job, you correct for the light source. In designing for a 40° 
incandescent beam, the mirror makes 36° width and 4° width are 
contributed by the light-source. One could work well with the 
incandescent lamp. 

Mr. Egeler: From an artistic standpoint it seems undesirable 
to have extremely sharp shadows. In connection with the application 
of these units I should like to ask whether these relatively sharp 
shadows are not objectionable, and whether the units are not used 
with diffusers that eliminate the shadows. Is there an extremely 
wide spread of the beam with a sharp shadow or a good control of the 
light which is then diffused? 

. Mr. Palmer: I can answer Mr. Egeler's question by saying 
that in the first place it isn't often that just one of these lamps is 
used at a time. In that case, one would help out the shadows of the 
other. If it was necessary to have a diffused shadow without showing 
the peculiar effect seen on the screen, it could be accomplished by 
putting a ground glass on the lamp for the time being. Even with 
the ground glass I believe one would get more light than from an 
ordinary parabohc mirror without the glass. 

Mr. Jenkins: I should hke to ask if this same development has 
been appUed to elhpsoidal reflectors? 

Mr. Benford: That would be entirely possible if you wanted 
to concentrate not to the maximum degree but over some definite 
area. I think that would be very useful, and I don't see any difficulty 
in carrying out the design. 

Mr. L. a. Jones: I should like to call attention to a polygonal 
reflector which was described some time ago in these Transactions 
This was not designed from the same view point as that taken by 
Mr. Benford. The reflectors I refer to were designed specifically for 
flood light, that is obtaining fairly uniform illumination over a 

Polygonal Floodlight Mirror — Benford and Palmer 121 

relativel}^ large area. These polygonal reflectors were constructed 
for use with 3000 watt tungsten lamps and we have been using 45 
of them in a color motion picture studio in Rochester. They have 
proven very satisfactory for flood lighting and have a very high 
coefficient of utilization. In general a group of nine of these are 
assembled fairly close together, but even so the spatial distribution 
is relatively great so that the shadows formed are not very distinct. 
In case a sharply defined shadow is wanted we find it necessary to 
use a spot light such as a 10 KW lamp mounted in a parabolic search 
light reflector. 

Mr. Mayer: I should like to gather more information with 
regard to concentrating a beam of light from such a mirror. Would 
it be possible to concentrate the light by mirrors, that is, the smaller 
the individual mirror and the more of them, the greater the con- 

Mr. Benford: Yes. 

Mr. Richardson: Is it not a fact that the shadow effect is one 
application of the umbra and penumbra? 

Mr. Benford: Yes. 

Drs. A. R. Irvine and M. F. Weyman report (J. Amer. Med. 
Assoc.) that more eye-fatigue was caused by 45 minutes reading 
than view^ing black and w^hite motion pictures for II/2 hours, one 
hundred and fifty persons being examined. No less than 68 per 
cent of the subjects showed a 43 per cent loss of acuity of vision 
after 45 minutes reading and only 21 per cent after seeing the 
pictures. ''An interesting side-light on this observation was that 
when a group had been reading for 45 minutes and w^as sent 
immediately into a projection room, and view^ed a picture for 
11/2 hours, 83 per cent of those who had showed a fall showed an 
improvement after seeing the picture." This is explained by as- 
suming that the subject was bodily tired or totally fatigued on 
entering the room, and the entertainment of the picture pro- 
vided relaxation for them. In other words when your brain and 
eyes are tired 'go to the movies.' In another group of 60 persons 
it was found that 53 per cent showed loss of acuity after seeing 
black and w^hite pictures, while only 48 per cent showed loss of 
acuity after seeing colored pictures of the Technicolor type. In 
another group of 153 people there was no difference in black and 
white and colored pictures. (Sci. Amer. 1927, 83, 343.) 


Raymond Sylvester Peck was born at Ridgetown, Ontario, 
Canada, on February 2, 1886. He was one of the six children of 
Mr. and Mrs. W. R. Peck, the former a well known hotel man in that 
district. He was a member of one of the oldest and best known 
families in the southwestern section of Ontario. 

At an early age his family moved to Chatham, Ontario, where 
Raymond Peck was educated in the public and high schools. On 

graduation from his studies he 
commenced his career as a 
journalist with the old Windsor 
Times which is now the Border 
Cities Star. With this paper 
he rose to the post of City 
Editor and later removed to 
Detroit, Michigan, where he 
became associated with the 
editorial staff of the Detroit 
Free Press. After some years 
with this paper he entered the 
advertising field and became 
connected with the Nash Mo- 
tor Company at Kenosha, Wis- 
consin, in this capacity later 
moving to the southern States 
for this concern. 

In 1918 he returned to Can- 
ada to become publicity direct- 
or of the Canadian Universal 
Film Company with headquar- 
ters at Toronto and later editor 
of the Motion Picture Digest, 
Canada's foremost motion pic- 
ture trade paper. 
In 1919 he was appointed to the Governmental Service as Film 
Editor of the Exhibits and Publicity Branch of the Federal Depart- 
ment of Trade and Commerce in Ottawa from which grew the Cana- 
dian Government Motion Picture Bureau. In 1920 on the retirement 
of B. E. Norrish from the directorship of this Bureau he was appointed 
to take charge of the Bureau, a position he held until his death on 
May 27, 1927. 

In religion Mr. Peck was a Presbyterian. He was a leading 
member of the Windsor Lodge of the Masonic Order, an ex-official of 
the Ottawa Rotary Club, a leading m^ember of the Y.M.C.A. and 


other community and sporting organizations. At the time of his 
death he was a Governor of the S.M.P.E. He was a talented musician 
and was past president of the Ottawa South Community Orchestra 

Raymond Peck was one of the outstanding figures in the motion 
picture industry in Canada and well known in its circles in the 
United States and Europe. To him must be allotted the greatest 
amount of credit for having developed the Canadian Government 
Motion Picture Bureau from a little known and little thought of 
branch of the Canadian Civil Service to the largest and perhaps the 
best known governmental film organization in. the world. 

It was he who saw inestimable value of motion pictures as a 
means of the dissemination of information regarding Canada through- 
out the world as a means of advertising the country, its resources, 
industries and attractions, and as a means of encouraging settlers and 
visitors ; and from his efforts grew an organization that holds today a 
unique and prominent place in the motion picture industry. From a 
purely local organization producing a few technical and advertising 
films each year for domestic use he developed a large film producing 
and distributing organization with a yearly output of milHons of 
feet of film that are circulated throughout the world bringing Canada 
before the eyes of the people of all nations in the most telling way. 

The late Mr. Peck took a leading part in encouraging the pro- 
duction of films in Canada and had much to do with interesting large 
American concerns in the production of films in the Dominion. He 
was an expert in distribution matters and his opinions were called 
for all over the British Empire. Several years ago his services were 
loaned to the British West Indies and for this section of the Empire 
he made a series of very fine films which have since been used to 
advertise these colonies. 

Under the direction of the late Mr. Peck the Bureau developed 
from a practical nonenity that was an expense to the Canadian 
people with little return, to a large and efficient organization which 
in the past few years has more than paid its own way, its revenue 
more than defraying the cost of its operation while doing incalculable 
good in spreading the story of Canada and its opportunities and 
attractions throughout the civilized world. 


Abbott, P, M. (M). 
Motion Picture News, Inc. 729 7th 
Ave., New York, N. Y. 
Alexander, Don M. (M). 

Alexander Film Co., Denver, Colo. 
Aller, Joseph (M). 

Rothacker Aller Lab. 5515 Melrose 
Ave., Los Angeles, CaHf. 
Australian Film Co., 

729 Seventh Ave., New York, N. Y. 
Bach, Bertra J. 

Province of Ontario Pictures, 
Trenton, Ontario, Canada. 
Ball, Joseph A. (M). 
Technicolor M. P. Corp., 1006 N. 
Cole Ave., Hollywood, CaUf. 
Barrier, Paul L. (M). 

Path^ Cinema 30 Rue des Vignerons 
Vincennes, (Seine), France. 
Barleben, Karl A. (A). 

American Photography. 27 Dart- 
mouth St., Boston, Mass. 
Barrell, Chas. W. (M). 

c/o Western Electric Co., 120 West 
41st St., New York, N.Y. 
Barrows, Thad C. (A). 

Metropolitan Theater, Boston, 
Bassett, Preston R. (M). 

Sperry Gyroscope Co., Manhattan 
Bridge Plaza, Brooklyn, N. Y. 
Bateholz, C. F. (M). 

Director Visual Instruction, General 
Electric Co., Schenectady, N. Y. 
Beatty, a. M. (A). 

684 Franklin Ave., Nutley, N. J. 
Becker, Albert (A). 
National Theater Supply Co., 146 
Pearl St., Buffalo, N. Y. 
Benford, Frank A. (M). 
Illuminating Eng. Lab. General 
Electric Co., Schenectady, N. Y. 
Bertram, E. A. (A). 
Rothacker Film Mfg. Co., 13S9 
Diversey Parkway, Chicago, 111. 
Bethell, James G. (A). 
Kiddle & Morgeson, 115 Broadway 
New York, N. Y. 
Bird, Wm. H. (M). 

Regina Films Ltd., Banner Building, 
Saskatchewan, Canada. 
Blair, George A. (M). 
Eastman Kodak Co., 343 State St. 
' Rochester, N. Y. 
Blumberg, Harry S. (M). 
Philadelphia Theater Equipment 
Co., 262 North 13th St., Phila- 
delphia, Pa. 

BoRNMAN, Carl (A). 
Ansco Camera Works, Johnson City, 
N. Y. 
Bowen, Lester (A). 
440 Terrace Ave., Hasbrouck Heights, 
Bradshaw, a. E. (A). 

1615 Sixth Ave., Tacoma, Wash. 
Brenkert Karl M. (M). 

Brenkert Light Projection Co., 7348 
St. Aubin Avenue, Detroit, Mich. 
Briefer, Michael (M). 

Atlantic Gelatin Co., Woburn, Mass. 
Bristol, William H. (M). 

Bristol Company, Waterbury, Conn. 
Brown, Douglas (A). 

121 East 40th St., New York, N. Y. 
Buckles, J. O. (A). 

Southern Theater Equipment Co., 
1912 West 12th St., Oklahoma 
City, Okla. 
Burchett, C. W. (A). 

255 Golden Gate Ave., San Fran- 
cisco, Cahf. 
Burnap, Roberts. (M). 

Edison Lamp Works, Harrison, N. J. 
Bush, Herman (A) 
1327 S. Wabash Ave., Chicago, 111. 


Cooper-Hewitt Electric Co., 730 
Grand St., Hoboken, N. J. 
Campe, H. a. (M). 

Westinghouse Electric & Mfg. Co., 
5550 Raleigh St., Pittsburgh, Pa. 
Candy, Albert M. (M). 

Westinghouse Elec. & Mfg. Co., 
E. Pittsburgh, Pa. 
Capstaff, John G. (M). 
Eastman Kodak Co., Kodak Park, 
Rochester, N. Y. 
Carleton, H, 0. (A). 

Duplex M. P. Industry Inc., Harris 
Ave. & Sherman St., Long Island 
City, N. Y. 
Carpenter, Arthur W. (A). 
Carpenter-Goldman Lab., 350 
Madison Ave., New York, N. Y. 
Cavaliere, Nicholas (A). 

342 Atlantic St., Stanford, Conn. 
Chanier, G. L. (M). 

Pathe Exchange, 1 Congress St., 
Jersey City, N. J. 

ClFRE, J."S. (M). 

United Theater Equipment Co., 
26-28 Piedmont St., Boston, Mass. 
Clark, Chas. H. (M). 

60 Grand St., New York, N. Y. 


List of Members 


Clark, James L. (M). 

Akeley Camera Inc. 244 West 49th 
St., New York, N. Y. 
Clarke, Eric T. (A). 

Eastman Theater, Rochester, N. Y. 
CoFFMAN, Joe W. (A). 

710 St. Nicholas Ave., New York, 
N. Y. 
Cohen, Emmanuel (M). 

145 West 55th St., New York, N. Y. 
Cohen, Joseph H. (M). 
Atlantic Gelatine Co., Hill St. 
Woburn, Mass. 
CoNKLiN, Robert (A). 

300 W. 4th St., New York, N. Y. 
Cook, Otto W.(.V/) 
Research Lab. Eastman Kodak Co. j 
Kodak Park Rochester, N. Y. 
Cook, Willard B. (M). 

Kodascope Libraries Inc., 35 West 
42nd St., New York, N. Y. 
CowELL, Paul J (A/). 

National Carbon Co. Inc., P. O. 
Box No. 4n0, Cleveland, Ohio. 
Cowling, Herford T. (M). 

Eastman Kodak Co., Rochester, 
N. Y. 
CozzENS, Louis S. (A). 
Chemical Dept., Redpath Labs., 
Pathe-Du Pont De Nemours Co., 
Parlin N. J. 
Crabtree, John I. (M). 
Eastman Kodak Co., Kodak Park, 
Rochester, N. Y, 
Cuffe, Lester E. (A). 
Famous-Plaj^ers Laskv Studio, 1520 
Vine St., Hollywood, Calif. 
CuMMiNGS, John S. (A). 

Cummings Laboratory, 23 West 60th 
St., New York, N.Y. 
CuRLE, Chas. E. (A). 

1902 East 12th St., Chattanooga, 
Danashew, Anatole W. (A). 

Government Motion Pictures, Prech- 
istenka, Obulkov per No. 6, Apt. 
8, Moscow, Russia. 
Davidson, L. E. (M). 

Spencer Lens Co., Buffalo, N. Y. 
Denison, Earl J. (M). 

Famous Players-Laskv Corp., 485 
Fifth Ave., New York, N. Y. 
Depue, Oscar B. (A). 

The Burton Holmes Labs., 7510 N. 
Ashland Ave., Chicago, 111. 
DeTartas, Augustus R. (A). 

Grosvenor St. & East Drive, Douglas 
Manor, L. I. N. Y. 
De Vault, Ralph P. (M). 
Acme Motion Picture Projector Co., 
1134 W. Austin Ave., Chicago, 111. 

De Witt, H. N. (A). 
Pathescope Co. of Canada Ltd., 156 
King St. W., Toronto, Ontario, 
Dick, A. C. (A). 

Westinghouse Lamp Co., Bloom- 
field, N. J. 
Donaldson, Wm. R. (A). 
P. N. Miller Co., 30 Pine St., 
New York, N. Y. 
DowNES, A. C. (M). 

c/o National Carbon Co., Carbon 
Development Laboratory, Cleve- 
land, Ohio. 
DuNBAUGH, Geo. J. (A). 

Helios Corp., 7332 Kimbark Ave., 
Chicago, 111. 
Dunning, Carroll D. (A). 

F.B.O. Studios, Gower St., Holly- 
wood, Cahf. 
Earle, Robert D. (M). 

Bay State Film Co., Sharon, Mass. 
Edwards, George C. (A). 

American Projectionist, 101-21 Sev- 
enty Eight St., Ozone Park., Long 
Island, N. Y. 
Egeler, CarlE. (ilf). 

National Lamp Works, Engineering 
Dept., Nela Park, Cleveland, Ohio. 
Emslie, Emmett K. (A). 

Buick Motor Co., Factory No. 17, 
FHnt, Mich. 
Faulkner, Trevor (A). 

Famous Players-Lasky Corp., 485 
Fifth Ave., New York, N. Y. 
Fernandez, Cecil (A). 

Trumbull Amusement Co. of St. 
Petersburg, P. O. Box 7305, 
West Tampa, Fla. 
Fleischmann, Leon (M). 

c/o Loew Inc., 1540 Broadway, New 
York, N. Y. 
Flickinger, Edward (A). 

Ford Motor Co., of Canada. 204 
Maple St., Windsor, Ontario, 
Flynn, Kirtland (M). 

Celluloid Co. of Newark, 290 Ferry 
St., Newark, N. J. 
De Forest, Lee (M). 

318 East 48th St., New York, N. Y. 
Fritts, Edwin C. (M). 

Eastman Kodak Co., 343 State 
Street, Rochester, N. Y. 
FuLCHER, Edgar J. (A). 

157 Albert Street East, Saulte 
Ste. Marie, Ontario, Canada. 
Fulton, C. H. (A). 
c/o E. E. Fulton Co., 1018 South 
Wabash Ave., Chicago, 111. 
Gage, Henry P. (M). 

Corning Glass Works, Corning, N. Y. 


List of Members 

Gage, Otis A. (A). 

Corning Glass Works, Corning, N. Y. 
Gaumont, Leon (M). 

Gaumont Co., 57 Rue Saint Roch, 
Paris, France. 
Geib, E. R. (A). 

National Carbon Co., Cleveland, 
Gelman, J. N. (M). 

3439 Jay St., Cincinnati, Ohio. 
Glover, Harry M. R. (M). 

Gundlach Manhattan Optical Co., 
Rochester, N. Y. 
Gerrard, Wm. C. (A). 

Famous Players-Lasky Corp., 6th & 
Pierce Aves., Astoria, Long Island, 
N. Y. 
GoFF, Daniel J. (A). 

3668 S. Michigan Ave., Chicago, 111. 
Goldberg, J. H. (A). 

3535 Roosevelt Rd., Chicago, 111. 
Goldman, Lyle F. (A). 

Carpenter-Goldman Lab., 350 
Madison Ave., New York, N. Y. 
Gordon, Irl(A). 

Orpheum Theater, Akron, Ohio. 
Gray, Arthur H. (A). 

Lancaster Theater, Lancaster & 
Causeway Sts., Boston, Mass. 
Green, Walter E. (M). 
International Projector Co., 90 Gold 
Street, New York, N. Y. 
Greene, Chauncey L. (A). 

3141 Harriett Ave., S., Minneapohs, 
Gregory, Carl Louis (M). 

76 Echo Ave., New Rochelle, N. Y. 
Griffin, Herbert (Af). 

International Projector Corp., 90 
Gold St., New York, N. Y. 
Halverson, C. a. B. (M). 

General Electric Co., West Lynn, 
Hamister, Victor C. (M). 

National Carbon Co., W. 117th & 
Madison Ave., Cleveland, Ohio. 
Handschiegl, Max (M). 

1040 McCadden Place, Los Angeles, 
Harrington, Thomas T. (A). 
University of CaUfornia, 2242 Grove 
St., Berkeley, Calif. 
Hedwig, William, K, (M). 

W. K. Hedwig M. P. Enterprises, 
Inc., 48 Congress Ave., Flushing, 
Long Island, N. Y. 
Hertner, J. R. (M). 

Hertner Electric Co., 1905 West 
114th St., Cleveland, Ohio. 
HiBBERD, Frank H. (M). 

Duplex Motion Picture Industries, 
Harris Ave. & Sherman St., Long 
Island, N. Y. 

Hickman, Kenneth (M). 
Eastman Kodak Co., Kodak Park, 
Rochester, N. Y. 
Hill. Roger M. (M). 

1403 New York Ave., N.W., Wash- 
ington, D. C. 
Holman, Arthur J. (A). 

56 Cummings Rd., Brookline, Mass. 
HoRNiDGE, Henry T. (A). 

ECiddle & Morgeson, 115 Broadway, 
New York, N. Y. 


Howell's Cine Equipment Co., Inc., 
740 7th Ave., New York, N. Y. 
Howell, A. S. (M). 

Bell & Howell Co., 1801 Larchmont 
Ave., Chicago, 111. 
Hubbard, Roscoe C. (M), 
Erbograph Co., 203 West 146th St., 
New York, N. Y. 
Hubbard, Wm. C. (M). 

Cooper-Hewitt Electric Co., 95 
River St., Hoboken, N. J., Mail 
to 111 W. 5th St., Plainfield, N. J. 
Huesgen, Charles K. (A). 
Herbert & Huesgen, 18 East 42nd 
St., New York, N. Y. 
Isaac, Lester B. (A). 

Marcus Loew, Inc., 1540 Broadway, 
New York, N. Y. 
IvES,F.E. (M). 

1808 N. Park Ave., Philadelphia, Pa. 
Jeffrey, Frederick A. (A). 
9 Giles St., Toorak, Adelaide, South 
Jenkins, Francis C. (M). 
_ 5502 16th St., Washington, D. C. 
John, Robert (M). 

DayHght Film Corp., 229 West 28th 
St., New York, N. Y. 
Jones, John G. (M). 

Eastman Kodak Co., Kodak Park, 
Rochester, N. Y. 
Jones, John M. (A). 

433 Beaumont Ave., Charlotte, N. C. 
Jones, L. A. (M). 

Eastman Kodak Co., Kodak Park, 
Rochester, N. Y. 
Johnstone, W. W. (A). 

Bausch & Lomb Optical Co., 28 
Geary St., San Francisco, Cahf. 
Joy, John M. (M). 

Fox Film Corp., 850 Tenth Ave., 
New York, N. Y . 
Kelley, Wm. V. D. (M). 

Kelley Color Films Inc., 1040 
McCadden Place, Los Angeles, 
Keuffel, Carl W. (A). 

Keuffel-Esser Co., 3rd & Adams St., 
Hoboken, N. J. 

List of Members 


KiLBORx. Orsox (A). 

Peroff Pictures, Inc.. 67 West 44th 
St., Xew York. X. Y. 
Kroesex, J. C. (3/). 

Edison Lamp Works, Harrison, N. J. 
KUXZMAX. Wm. C. 01) . 

Suite 2-2992 West Uth St., Cleve- 
land, Ohio. 


Brenkert Light Projection Co., 7348 
St. Aubin Ave., Detroit, Mich. 
Lair, CUf). 

Pathe Cinema 30 Rue des Vignerons, 
Yincennes, France. 
Laxg, C. J. (M). 

Lang Mfg. Works, Clean, N. Y. 
La Rue, Mervix W. U)- 

Bell & Howell, 1801 Larchmont 
Ave., Chicago. 111. 
Levexthal, J. F. (M). 

1540 Broadway, New York, N. Y. 
Lewis, William W. (A). 
J. E. McAuley Mfg. Co., 554 West 
Adams St., Chicago, 111. 
Little, W. F. (M). 

Electrical Testing Lab., 80th St. & 
East End Ave., New York, X. Y. 
MacGregor, Charles D.(A). 

Griffin Opera House, Iving Street 
West, Chatham, Ontario, Canada. 
McAuLET, J. E. (M). 

McAulev Mfg." Co., 552 W. Adams 
St., Chicago, lU. 
McCLixtock, Xormax(J.). 

504 Amberson Ave., Pittsburgh, 
McGixxis; F. J. (A). 

Box 541, Palm Beach, Fla. 
McGuiRE, Percival a. (M)- 

International Projector Corp., 90 
Gold Street, Xew York, X. Y. 
McXabb, J. H. (3/). 

Bell & Howell Co., 1801 Larchmont 
Ave., Chicago, 111. 
Maire, Hexry J. {A). 

2152 Center Ave., Fort Lee, X. J. 
Maxheimer, J. R. (3/). 
E. J. Electric Installation Co., 155 
East 44th St., Xew York, X. Y. 
Marette, Jacques (3f). 

17 Boulevard Haussmann, Paris, 
Matlack, Claude C.{A). 
Matlack Corp., 323-23rd Street, 
Miama Beach, Fla. 
Mayer, Max (3/). 

218 West 42nd St., Xew York, X. Y. 
Mechau, Emil {A). 

E. Leitz Inc., Rastatt, Germanv. 
Mees, C. E.K. (3/). 
Eastman Kodak Co., Kodak Park, 
Rochester, X. Y. 

Miller, Arthur P. (3/). 

Chicago Film Laboratory 1322 Bel- 
mont Ave, Chicago, 111. 
MisTRY, D. L. (A). 
24 Xepean Rd., Malabar Hill, Bom- 
bay 6, India. 
Mitchell. Geo. A. (3/). 

5729 Ridge Ave.. Chicago. III. 
Moloxey, Fred G. (3/) 
Helios Corp., 7544 S. Chicago Ave., 
Chicago, 111. 
Murray, Wm. W. (A). 

528 Madison Ave., Scranton, Pa. 
Xelsox. Otto (A). 

Xational Cash Register Co., Davton, 
Xixox, I VAX L. (3/). 

Bausch & Lomb Optical Co., Ro- 
chester, X. Y. 
XORLIXG, J. A. (A). 

Loucks & Xorling, Inc., 723 Seventh 
Ave., Xew York, X. Y. 
XORRISH, B. E^. (3/). 

Associated Screen Xews, 12 Mayor 
St., Montreal, Canada. 
O'Briex, Mortox D. 

[Marcus Loew Inc., 1540 Broadway, 
Xew York, X. Y. 
Olesex, OttoK. (3/). 

1645 Hudson Ave., Hollvwood, 
OwExs, Freemax H. (A). 

70 Lafayette St., Xew York, X. Y. 
Palmer, M. W. (3/). 
Famous Players-Lasky Corp., 6th & 
Pierce Aves., Long Island City, 
X. Y. 
Pattox, George E (M) 

Pro\'ince of Ontario Pictures, 46 
Richmond St. West, Toronto, On- 
tario, Canada. 
Pexxow, Willis a. (A). 

Perfection Arc Co., 14th St. and 
Xorth Ave., Milwaukee, Wis. 
Peytox, Johx T. (A). 

623 West Wheeler St., Oklahoma 
City, Okla. 
Phelps, L. G. (3/). 

818 Chapel St., Xew Haven, Conn. 
Phillimore. Chas. E. (A). 

Bell & Howell Co., 1801 Larchmont 
Ave., Chicago, 111. 
Plaxskoy, Leoxti (3/). 

9 Rue Boissy d'Anglais, Paris, 
PoMEROY, Roy J. (3/). 

Famous Plaj^ers-Lasky Studio, 1520 
Vine St., HoUywood, CaKf. 


List of Members 

Porter, L. C. (M). 
Edison Lamp Works, Harrison, 
Posey, O. D. {A). 
Southern Enterprise Inc., 583^ Cone 
St., Atlanta, Ga. 
PowRiE, John H. (M). 

Warner Research Lab., 461 Eighth 
Ave., New York, N. Y. 
Pratchett, a. B. (A). 

Caribbean Film Co., Estrada Palma 
112, Havana, Cuba. , . 
Price, Arthur (A). 

130 Denhoff Ave., Freeport, L. I. 
Price, Hickman (A). 

M. P. Producers & Distributors of 
America, 469 Fifth Ave., New 
York City. 
QuiNLAN, Walter (M). 

Fox Film Corp. 55th St. & 10th 
Ave., New York, N. Y. 
Rabbell, Wm. H. (M). 

Sullivan's Theater Ticket Serv. Co., 
729 7th Ave., New York, N. Y. 
Raess, Henry F. (A). 

Warner Research Lab., 461 Eighth 
Ave., New York, N. Y. 
Ransdell ussellR. (A). 

5408 Pasep Boulevard, Kansas City, 
Raven, A. L. (M). 

Raven Screen Co., 1476 Broadway, 
New York, N. Y. 
Rayton, Wm. B. (M). 
Bausch & Lomb Optical Co., Roches- 
ter, N. Y. 
Redpath, Wm. (M) 

156 King St. W., Toronto, Canada. 
Reich, Carl J. (M) 

Gundlach-Manhattan Optical Co., 
739 Clinton Ave., Rochester, N. Y. 
Renwick, F. F. (A). 

Ilford Ltd., Ilford, Essex, England. 
Richardson, Frank H. (M). 

Moving Picture World, 516 Fifth 
Ave., New York, N. Y. 
Robinson, Karl D. (A). 

2 West 16th St., New York, N. Y. 
Rogers, Rowland (A). 

Picture Service Corp., 71 West 23rd 
St., New York, N. Y. 
Romell, F. J. (A). 

Romell Motion Pictures, Inc., 908 
Schmidt Bldg., Cincinnati, Ohio. 
Rosenberger, Heinz (A). 

Rockefeller Institute, 66th St. & 
Avenue A, New York, N. Y. 
Rt)ss, Oscar A. (A). 

Room 907, 79 West 45th St., New 
York, N. Y. 
Rossman, Earl W. (M). 
City Club of New York 55 West 
44th St.. New York, N. Y. 

Ruben, Max (A). 

2647 W. Philadelphia Ave., Detroit, 
Rubin, Harry (A). 

Rialto Theater, Broadway & 42nd 
St., New York, N. Y. 
Rudolph, Wm, F. (A). 

Famous Players-Lasky Studio, 1546 
Argyle St., Los Angeles, Calif. 
Ruot, Marcel (A). 

Path6 of France Ltd., 5 Lisle Street, 
London, W. I., England. 
Samuels, Irving (A). 

Automatic Devices Co., Hunsicker 
Bldg., AUentown, Pa. 
Savage, F. M. (A). 

3 Potter Place, Weehawken, N. J. 
Scanlan, G. a. (A). 

Du Pont De Nemours Co., Box 86, 
Parlin, N. J. 
Shackelford, J. B. (A). 

6620 St. Francis Court, Hollywood, 
Schmitz, Ernest C. (A). 

Kodak Co., Cine Dept., 39 Avenue 
Montaigne, Paris, France. 
Sease, Virgil B. (M). 

Du Pont-Path4 Film Mfg. Co., Par- 
lin, N. J. 
Senner, Adolph G. (A). 

Herbert & Huesgen Co., 18 East 
42nd St., New York, N. Y. 
Serrurier, Iwan S. (M). 

1803 Morgan Place, Los Angeles, 
Sheppard, Samuel E. (ikf). 

Eastman Kodak Co., Kodak Park, 
Rochester, N. Y.- 
Shimek, John A. (A). 

Bell & Howell Co., 1801 Larchmont 
Ave., Chicago, 111. 
SiSTROM, William (M). 

Cecil B. DeMille Studio. Culver 
City, California. 
Sloman, Cheri M. (A). 

East 3000 Woodbridge St., Detroit, 
Smith, J. Grove 

Dominion Government, Plaza Build- 
ing, Ottawa, Canada. 
Spence, John L. (M). 

Akeley Camera Co., 250 West 49th 
St., New York, N. Y. 
Sponable, Earl I. (M). 

277 Park Ave., Apt. 2, W. New York, 
N. Y. 
Stark, Walter E. (A). 

Colorart Studio, 415 Madison Ave- 
nue, New York, N. Y. 
Stewart, Victor A. (M). 

Fox Film Corporation, 850 Tenth 
Ave., New York, N. Y. 

List of Members 


Stone, George E. (M). 

Carmel, Monterey County., Calif. 
Story, W. E. Jr. (M). 

17 Hammond St., Worcester, Mass. 
Struble, Cornelius D. (M). 
National Theater Supply Co., 624 
So. Michigan Ave., Chicago, 111. 
Summers, John A. (M). 

Edison Lamp Works, Harrison, N. J. 
SwAAB, Mark L. {A). 
L. M. Swaab & Son, 1325 Vine St., 
Philadelphia, Pa. 
Tamlin, B. G. (A). 

Jeffery Laboratory, 9 Giles St., Rose 
Park, S. Australia. 
Theiss, JohnH. (M). 
E. L Du Pont De Nemours, 35 W. 
45th St., New York, N. Y. 
ToPLiFF, Geo. W. (A). 

Ansco Co., Binghamton, N. Y. 
Townsend, Lewis M. (M). 

Eastman Theater, Rochester, N. Y. 
Travis, Charles H. (A). 
1061 University Place, Schenectady, 
. N. Y. 
Victor, A. F. (M). 

Victor Animatograph Co., 242 W. 
55th St., New York, N. Y. 

Vinten, Wm. C. (M). 

89 Wardour St., London W. I., Eng- 
VoLCK, A. George (M). 
Cecil B. DeMille Studio, Culver City, 
Wall, Edward J. (M) 

38 Bromfield St., Wollaston, Mass. 
Waller, Fred (M). 

Famous Players-Lasky Corp., 6th 
& Pierce Ave., Long Island, N. Y. 
Ward, G. Bert (M). 

Ward Cine Lab., Inc., 216 Nine- 
teenth St-., Union City, N. J. 
Wescott, W. B. (M). 

Dover, Mass. 
Williamson, Colin M. (A). 
WilHamson Manufacturing Co. Ltd., 
Litchfield Gardens, London, N. W. 
10, England. 
WoosTER, Julian S. (A). 

233 Broadway, New York, N. Y. 
Wycoff, Alvin a. (A). 

Famous Players-Lasky Corp., As- 
toria, L. I. N. Y. 
ZlEBARTH, C. A. (M). 

Bell & Howell Co., 1801 Larchmont 
Ave., Chicago, 111. 

if=n i =11 M iF= ir== II L-=ii ^i r=nr 







Volume XI, Number 30 

MEETING OF APRIL 25, 26, 27, 28, 1927 

lklr=n f====ii =1 1 11 i r= if===ii =i f=ir^ 

Copyright, 1927, by 

Society of 

Motion Picture Engineers 

New York. N. Y. 


Engineering Societies Building 
29 West 39th St., New York, N. Y. 

- Papers or abstracts may be reprinted if credit is given to the Society of 
Motion Picture Engineers. 

The Society is not responsible for the statements of its individual members. 


H. P. Gage 

L. 0. Porter 

WiLLAKD B. Cook 

Past President 
L. A. Jones 

M. W. Palmer 

W. C. Hubbard 

Board of Governors 
W. B. Cook 
L. A. Jones 
W. C. Hubbard 
L. C. Porter 
F. H. Richardson 
J. C. Kroesen 
J. I. Crabtree 
J. H. Theiss 
J. A. Ball 

A. M. Beatty 
Louis Cozzens 



Advertising and Fublicity 
P. A. McGuire, Chairman 

George Edwards 
W. V. D. Kelley 

John H. Kurlander 
J. 0. Kroesen 

Carl L. Gregory 
F. H. Richardson 

K. C. D. Hickman, Chairman 

John H. Theiss 
W. C. Vinten 

Herbert Griffith 
J. G. Jones 

Standards and Nomenclature 
Henry P. Gage, Chairman 
r. H. Richardson 

C. M. Williamson 
C. A. Ziebarth 

J. A. Ball 

J. I. Crabtree, Chairman 
C. E. Egeler 

L. A. Jones 

J. I. Crabtree 
B. P. Devault 
Carl L. Gregory 

C. E. Egeler, Chai/rman 

K. C. D. Hickman 
A. S. Howell 

W. V. D. Kelley 
John H. Kurlander 
Rowland Rogers 

J. I. Crabtree 

E. J. Wall, Chairman 

K. C. D. Hickms 


By Loyd a. Jones* 

I Introduction 
II Fundamental Laws: 

A Reflection 

B Absorption 

C Transmission 

III Measurement, Graph Curves, Computations 

IV Filter Factor: 

A Integral method 
B Sensitometric method 
C Computation of exposure factors 
V Use of light filters with panchromatic film : 

A Orthochromatic reproduction of brightness: 


B Distorted reproduction of brightness: 

General rules for enhancement of depression 

Direction of distortion 

Magnitude of distortion. 

IN A previous communication^ the use of panchromatic film for 
motion picture purposes was discussed at some length. The 
fundamental principles involved in the photographic reproduction 
of the tonal scale, that is brightness and brightness differences, in 
the case of colored objects were outlined and attention called to 
some of the advantages arising from the use of panchromatic film 
for this purpose. The use of hght filters was mentioned briefly 
but no attempt was made to deal with this subject in detail. Since 
a thorough understanding of the nature of light filters and their 
use for obtaining a desired effect is essential to the attainment of 
the best results in the application of panchromatic film to various 
problems confronting the photographic worker, it seems desirable at 
this time to present a somewhat more complete and detailed treatment 
of the subject. Believing firmly in the premise that the nearest 
approach to perfection in the practice of a science can be attained 
with greatest facility and certainty through an adequate knowledge 
of the theoretical aspects of the subject, the first part of this paper 
* Research Laboratory of the Eastman Kodak Company. 



Transactions of S.M.P.E., August 1927 

will be devoted to a discussion of some of the fundamental principles 
involved in the use of hght filters. In the latter part the more practical 
phases of the subject will be dealt with and some data relative to the 
use of hght filters will be given. 

C B' 

Fig. 1. Diagram illustrating reflection, absorption and transmission. 

Fundamental Laws 
When radiation falls upon a transmitting material, such as a 
piece of glass, a part is reflected at the first surface, some is absorbed 
within the material, some is reflected at the second surface, and the 
remainder is transmitted. In case the material is not optically homo- 
geneous or contains particles of matter of refractive index differing 
from that of the material itself, some of the light after entering the 
material will be reflected, refracted, or diffracted, and emerge either 

Light Filters — Jones 137 

through the front or rear surface of both as scattered or diffused Hght. 
Such a material is said to be turbid or diffusing. Opal glass and the 
developed photographic image, which consists of particles of metalhc 
silver embedded in a matrix of gelatine, are typical examples of 
diffusing materials. Diffusing materials are not in general suitable 
for photographic light filters and hence this paper will deal only 
with materials of the optically homogeneous non-diffusing type. 

This case is illustrated schematically in Fig. 1 where the shaded 
area G represents a cross section through a transmitting material 
of thickness, x, and refractive index, n, bounded by the plane parallel 
surfaces CC and BB', 
Let Jo =the intensity of the incident radiation 

Ic = the intensity of radiation reflected at the first surface, CC 

la = the intensity of the absorbed radiation 

7i =the intensity of radiation incident on the second surface, 

lb =the intensity of radiation reflected at the second surface, 

Ix =the intensity of the transmitted radiation. 
The transmission, T, of the filter may be expressed in terms of 7o 
and /i by the expression 

T = ~ (1) 

The opacity, 0, is given by the relation, 

0=l/r (2) 

The optical density, D, is defined by the relation, 

1 /o 

D = logio = logio — = logio — (3) 

T I\ 

Surface Reflection. The intensity of the radiation reflected at 
the boundary surface between two media differing in refractive index 
may be computed by means of the Fresnel law of reflection, 
Tc Isin^Tz — r) Itan^Ti — r) 

Rc = — = ^ -\——^ (4) 

/o 2sin2(^+0 2tan2(i-r) 

in which i is the angle at which the radiation is incident upon the 
surface, and r denotes the angle of refraction. This general form 
may be simpHfied in case the radiation is incident normal to the 

i?c = - = (-— ), (5) 

138 Transactions of S.M.P.E., August 1927 

in which n is the refractive index of the material and is defined 
by the ratio 

sin i 
n = — (6) 

sm r 

In the case of hght filters as used in photography the departure 
from normal incidence is so little that no appreciable error results 
from the use of equation (5). The value of n, the refractive index, 
depends upon the wave-length of the radiation, hence Re also depends 
upon wave-length. The variation of n with wave-length in the case of 
glass and gelatine, the materials commonly used for fight filters, is 
so small as to be of fittle practical significance. Assuming that the 
wave-length range of interest in photographic work extends from 
350 m/x (the shortest wave-length transmitted by the glass of which 
photographic objectives are made) to 800 m^t (the longest wave- 
length to which photographic materials are sensitive) the variation 
in n for ordinary crown glass is from 1.535 (wave-length = 350 mju) 
to 1.511 (wave-length = 800 mju). This variation is less than 2 per 
cent, and since Ic is approximately 4 per cent of 7o it is evident that 
the variation with wave-length of the intensity of the radiation 
transmitted by the surface is for all practical purposes negfigible. 
For dry gelatine the variation of n with wave-length is of the same 
order of magnitude and hence for all practical purposes the use of 
equation (4) will give results of sufficient precision. By substituting 
in (4) the numerical values applying to ordinary crown glass we 



Ic = h{ =/oX. 0425 = 4. 25% of /o. 

\1. 519+1/ 

Assuming now that the absorption, la, of the material is negli- 
gibly small, this being true for visible wave-lengths in the case of 
thin layers of colorless glass or clear sheet gelatine, 7i becomes equal 
to Iq — Ic- Equation (4) may again be used for computing the re- 
flection at the second surface, BB'. This takes the form 

Using the numerical values for glass and solving it is found that 
76= 0.0404/0 

I. = h-{Ic+I,) . (7) 

Light Filters — Jo?ies 139 

Placing 7o equal to unity we obtain 

7^=1. 0-(0.0425X. 0404) 

= 1.0-0. 083=. 917. 

It is e\ddent therefore that the maximum intensity of any wave- 
length that can be transmitted through a filter having two glass 
air surfaces is only 91.7 per cent of the incident intensity. This 
8 per cent (approximate) loss resulting from the use of a single 
layer of glass or gelatine, since the refractive index of gelatine is 
practically equal to that of glass, is not as a rule serious, but if an 
attempt is made to obtain some desired result by use of two or more 
layers, the loss of intensity due to this reflection at the glass air or 
gelatine air surface may become serious. In computing the loss due 
to surface reflection in the case of two or more superposed layers of 
gelatine or glass, the rather laborious step by step method illustrated 
above may be avoided by use of the equation, 

T^=TiP (8) 

in which Ti is the transmission of a single surface, p denotes the 
number of surfaces involved, and Tp is the transmission for p surfaces. 
In terms of the notation used in this paper. 

For convenience in computing this equation may be expressed in 
logarithmic form, 

log rp = ^(iog/i-i(>g/o). 

In this treatment of the surface reflection losses no mention has 
been made of the multiple inter-facial reflections. The equation 
covering the case of multiple reflections takes the form of an infinite 
series. The magnitude of the successive terms of this series decreases 
so rapidly, even the second term being negligibly small, that the 
above form is entirely satisfactory for practical purposes. 

Absorption of Radiation. The absorption which occurs within 
a non-turbid transmitting material follows a logarithmic law in all 
cases, including gases, hquids, and solids. Thus if a given layer of 
material absorbs a certain fraction of the radiation the next layer 
of the same thickness will absorb the same fraction of that transmitted 
by the first. If each Isijei of unit thickness transmits a fraction 
T (or absorbs 1 — T) then a layer of thickness x will transmit a fraction 

140 Transactions of S.M.P.E., August 1927 

r*. This may be expressed in the form of Bouguer^s law,^ 

/. = /oe-"" (9) 

where Jx is the intensity of the radiation transmitted by a layer 
whose thickness is a;, a is a constant referred to as the absorption 
constant, and e is the base of natural logarithms. This form is con- 
venient for application to the cases of absorption by gases, liquids 
(not solutions), and solids, such as transparent or colored glasses 
in which the required variation of absorption characteristics is 
controlled by the thickness, x. 

In dealing with the solutions it is more convenient to use a 
somewhat modified form which is, 

I^-^he-'''' (10) 

in which c is the concentration of the solute in grams per unit volume, 
and X again denotes the thickness of the absorbing layer. 

A third form is particularly adapted to the case of dyed gelatine 

/x==/o^-- (11) 

in which c is the dye concentration expressed in grams per unit 
area; x the thickness factor, being implicitly included in c. 

It is known that some dyes in solution do not obey Bouguer's 
law but thus far^ no observations have been made which indicate 
a departure of dyed gelatine filters from equation (11). Results 
reported by Von Hiibl'* indicate that many dyes which in water 
solution depart from Bouguer's law follow precisely the form shown 
in equation (11) when incorporated in dry gelatine. 

Measurements, Graphic Representation, and Computation 

The absorption constant, a, is in general dependent upon the 
wave-length [a=/(X)] and the determination of the value of a for 
various wave-lengths provides adequate information relative to 
the absorbing characteristics of light filters. In theoretical work 
on dyes and in the manufacture of filters these values of a express 
the relation between wave-length and absorption in a form directly 
applicable to the problems involved, but in the more practical 
appUcation of filters to photographic problems it is usually more 
convenient to express the relationship between absorption or trans- 
mission and wave-length in a somewhat different form. 

Light Filters — Jones 


To determine quantitatively the absorption of a light filter 
for radiation of different wave-lengths a spectrophotometer is used. 
An essential element of this instrument is a device, such as a prism 
or diffraction grating, for dispersing or separating into its component 
parts the radiation from some suitable source (such as the electric 
arc or incandescent lamp) which emits many different wave-lengths. 
In this way a spectrum is formed and by means of a narrow sht 
suitably placed, radiation of any desired wave-length may be isolated. 
One-half of this monochromatic radiation is then allowed to fall upon 


2 80 



I .40 








Fig. 2. Spectrophotometric transmission curve of green filter. 

the filter being examined and the intensity of the radiation trans- 
mitted by the filter is measured by comparing it in a suitable photo- 
meter with the other half of the monochromatic beam which has not 
been subjected to the absorbing action of the filter. In this way 
values of transmission, T, where 

r = ^ (see Fig. 1), 

for a series of different wave-lengths are obtained. These values 
plotted as a function of wave-length give a curve which shows the 
absorption characteristics of the filter in graphic form. This is 
called a spectrophotometric curve. It is customary in plotting such 
a curve to multiply Ix/h by 100, thus expressing transmission in 
percentage. Such a curve is shown in Fig. 2, applying to a gelatine 
filter made by the use of toluidine blue. 

For many purposes the expression of absorption in terms of 
optical density, equation (3), is more convenient than in terms 

142 Transactions of S.M.P.E., August 1927 

of transmission. If it is desired to compute the spectral distribution 
of absorption for two superposed filters, the transmission values 
at each wave-length for the two filters must be multiplied together, 
while if density is used it is only necessary to add the values at 
corresponding wave-lengths. Moreover since, 

= -\ogT 

= -log — 

it is evident by comparison with equations (9), (10), and (11) 
expressing Bouguer^s law that: 

(a) In case of solids, liquids, and gases D is directly proportional 
to the thickness, x. 

(b) In case of solutions D is directly proportional to the product 
of concentration, c, (grams per unit volume) by the thickness, x. 
Hence if x is constant D is directly proportional to c and if c is 
constant, D is directly proportional to x. 

(c) In case of dyed gelatine D is directly proportional to c 
(grams per unit area) . 

This direct proportionahty of D to the various exponents 
in the Bouguer equations of course applies only to the value of 
D after correction for surface reflection. Density as computed 
from transmission measurements made in the usual manner include 
the intensity losses due to surface reflections. It is evident that the 
surface reflection factor is entirely independent of the concentration 
and thickness factors. The correction for surface reflection is easily 
made provided the refractive index is known. Thus for glass or 
gelatine the reflection loss for the two surfaces is approximately 
8 per cent, or 0.08, corresponding to a transmission of 0.92. This is 
independent of wave-length and equivalent to a density of (Z> = log 

^y^) 0.036. Hence by subtracting .036 from all density values the 

density due to absorption is obtained. These values are now directly 
proportional to the thickness or concentrations as indicated in the 
Bouguer equations. Having determined these densities due to 
absorption at any wave-length for one thickness, x, or concentration, 
c, ^the density due to absorption for any other concentration, c', 
or thickness, x\ can be computed by the simple procedure of multi- 

Light Filters — Jones 


In Fig. 3, curve A, the spectrophotometric density curve for 
the filter illustrated in Fig. 2 is shown. Now suppose it is desired 
to determine the effect upon the spectral absorption of increased 
concentration of dye used in making the filter. Let the required 
concentrations be 2 and 4 times that represented by curve A in 
which it may be assumed that concentration is x grams per unit 
area. Let Dx be the density at some particular wave-length X as read 

300 400 500 600 700 


Fig. 3. Spectrophotometric density curves of green filter, illustrating relation 
between density and concentration and effect of surface reflection. , 

from curve A, for concentration 2x the required density will be 
given by 

Z)\=[(Z)x-.036)2] + 0.036 

and for a concentration of 4x 

D'\=[(Dx- .036)4] + 0.036. 

Computing the necessary values for various wave-lengths and 
plotting, the curves B and C are obtained. It is interesting to compare 
the result obtained by increasing the concentration 4 times, curve C, 
with that obtained by using four layers of the original film as shown 
by curve A. This case is represented by curve D, the ordinates of 
which were obtained by multiplying the ordinates of curve A by 4. 


Transactions of S.M.P.E., August 1927 

It will be noted that the minimum density of curve C is appreciably- 
less than that of curve D, thus the transmission of filter C for the 
wave-length which it transmits most freely is greater than that of 
filter D. The filter obtained by increasing the concentration four 
times is therefore more efficient from the standpoint of high selectivity 
in absorption characteristics than that obtained by using four layers 
of film. 




I 1.5 








— c 



















Fig. 4. 

Spectrophotometric density curves of A red filter, B green filter, and C 
the green filter obtained by superposing A and B. 

The expression of the data in the form of density is also most 
convenient where it is desired to compute the spectral absorption 
obtainable by the superposition of two or more filters or the use 
of two or more dyes in the same solution or gelatine film. In the 
case of the superposition of the two sheets of dyed gelatine or pieces 
of glass it is only necessary to add at each wave-length the density 
values as determined directly by the spectrophotometer in terms of 
Jo and Ix' In case the addition is to be made by incorporating two 
dyes in the same solution or in the same sheet of gelatine it is apparent 
th9,t the appropriate correction must be made for any surface re- 
flection factor which may be included in the density values for the 
individual dye components. In Fig. 4, curve A, is shown the spectro- 

Light Filters — Jones 


photometric density curve of a yellow (blue absorbing) gelatine 
filter. Curve B shows the same characteristic for a blue-green (red 
absorbing) gelatine filter. Curve C is that obtained by adding the 
ordinates of A and B and shows the spectral absorption obtained 
by the superposition of one layer of each filter. Curves A and B 
intersect at the point p of which the density value is 0.25 (trans- 
mission =56.4%). The density of the superposed combination, 
curve C, at the corresponding wave-length is two times 0.25 or 0.50 








• / 






Fig. 5. Spectrophotometric density curve of "sharp cut" green filter. 

(transmission = 32%) . This is the minimum density value of C. 
Hence at the wave-length which is transmitted most freely by the 
combination only 32 per cent of the incident radiation is transmitted. 
This compound filter (curve C) is bright green in color and isolates 
fairly well the wave-length band from 500 to 600 mfx. A filter of 
much greater efficiency for this purpose can be made by incor- 
porating properly selected dyes in a gelatine film. Such a filter is 
illustrated by the curve in Fig. 5. This has maximum transmission 
at approximately the same wave-length as C (Fig. 4) this being 54 
per cent (D = 0.25), ahnost twice that of filter C. 

A similar low efficiency is usually encountered to a greater or 
lesser extent whenever an attempt is made to isolate some particular 


Transactions of S.M.P.E., August 1927 

spectral region by superposing two or more separate filters. This 
is due in part to the increasing loss in surface reflections as the 
number of separate filters is increased. Furthermore each filter is 
designed by the manufacturer to give some specific spectral absorption 
with maximum efficiency and to this end the best possible available 
dyes are selected. If some entirely different spectral absorption is 
required it is probable that dyes can be selected which will function 


















V \ 

\ \ 
\ \ 



\ \ 













400 500 


Fig. 6. Spectrophotometric curves illustrating "sharp cut" A, gradual cut 
"inefficient" filter B, and gradual cut efficient filter B'. 

with greater efficiency than can be obtained by combining two filters 
designed specifically to meet other requirements. 

The terms "sharp cut" and "gradual cut" are frequently applied 
as descriptive of light filters. The significance of these terms may be 
illustrated by reference to Fig. 6. Curve A is the spectrophotometric 
curve of a brilHant yellow gelatine filter. Its density at all wave- 
lengths greater than 480 mju is 0.1 (transmission = 86%). The ab- 
sorption at wave-lengths less than 480 m/>t increases rapidly so that 
at 460 mjLt its density is 1.5 (transmission = 3.1%). Such a filter is 
described as a "sharp cut" filter. It is evident therefore that the term 
"sharp cut" applies to a filter of which the absorption curve is steep, 
that is the rate of change of absorption with variation in wave-length 

Light Filters — Jones 147 

is great, or conversely the condition described as "sharp cut" appHes 
to the case where a relatively small change in wave-length is ac- 
companied by a large change in absorption. 

Curve B applies to a piece of amber glass and to such a filter 
the descriptive term "gradual cut" is applied. It will be noted that 
the wave-length band over which the change from its minimum to 
maximum density occurs is very broad, extending from 600 m/x to 
300 m/x. The slope of the absorption curve in this region of variable 
absorption is low and hence the filter is described as one having a 
"gradual cut." The transmission of this filter for the wave-length 
it transmits most freely is very low, being approximately 50 per cent 
(density = 0.3) in the region from 600 to 800 m/i. Filter A has a 
bright yellow color, while B has a hue slightly more orange and ex- 
hibits a dull "muddy" appearance. This term "muddy" is also used 
frequently as descriptive of light filters and indicates a relatively high 
general absorption for all wave-lengths in the visible region. The 
muddy appearance may be considered as due to an admixture of 
black in the filter. For instance let the dotted curve B' represent a 
filter having an absorption curve similar in shape to that of B but for 
which the density at all wave-lengths is .24 less than that of B. 
The maximum transmission of 5', in the wave-length band from 600 
to 690 m/x, is 90 per cent and such a filter has a clean brilliant ap- 
pearance although the dominant wave-length is somewhat longer 
than in the case of filter A thus giving filter B' a hue which is more 
orange. Now suppose that to this filter (curve B') is added a black 
dye, represented by curve C of such concentration as to give a density 
of 0.24 at all wave-lengths. The addition of C to B' gives B, and the 
B' filter is changed thereby from a clear brilliant yellow-orange to a 
dull "muddy" amber. "Muddiness" in a filter is therefore due to 
something equivalent to the addition of a black component and is an 
indication of high absorption in the wave-length region of maximum 
transmission and hence of low optical efficiency. 

Filter Factor 

When a filter which absorbs some of the radiation to which the 
photographic material is sensitive is placed over the lens of the camera, 
it is evident that an increase either in exposure time, in the lens 
aperture, or in the illumination incident on the object, must be made 
in order to obtain the same exposure on the negative as when no 
filter is used. If any two of these factors are constant then the ratio 


Transactions of S.M.P.E., August 1927 

of the third factor as required when using the filter, to the same factor 
without a filter is called i\iQ filter factor or the multiplying factor of the 
filter. This will be designated by the symbol F. An "eight times" 
filter is one for which the multiplying factor is 8, etc. 

The magnitude of the filter factor depends on the conditions 
under which the filter is used and its determination involves a 
knowledge of the spectral sensitivity of the photographic material, 
the spectral distribution of energy in the radiation which illuminates 























8 O 



.6 U 



2 C 


400 500 




Fig. 7. Spectrophotometric curves showing the relation between photographic 

sensitivity, D, energy distribution in daylight, 5, and transmission of radiation 

by photographic objective, C. 

the object, and the spectral absorption of all components of the 
optical system between the object and the photographic material. 
In Fig. 7 these various characteristics are shown in graphic form. 

Let the sensitivity of the photographic material be designated 
by the symbol A. Curve T> shows the spectral distribution of sensi- 
tivity for panchromatic motion picture negative film and may be 
represented formally by 

^=/(X) (14) 

At any particular wave-length, X, the ordinate of this curve will 
be represented by the symbol A\. Sensitivity, A, may be expressed 
in several different forms depending upon the problem to which the 
data are to be applied. For our present purpose it seems most logical 

Light Filters — Jones 149 

to define sensitivity as directly proportional to the density which is 
produced for a fixed development time by the action of a constant 
amount of energy (ergs per cm. sq.) of the various wave-lengths as 
indicated by the scale estabhshed on the X-axis. Curve D in Fig. 7 
represents the spectral distribution of sensitivity as defined in this 

The spectral distribution of energy in daylight is shown by 
curve B which may be represented formally by, 

/=/(X) (15) 

The ordinate of this curve at any wave-length, X, will be represented 
by the symbol J\. The curve as shown is computed from the data 
given in the previous communication^ (Fig. 7, p. 144). Measure- 
ments have shown that of the radiation incident on a horizontal 
plane so placed as to receive radiation from the entire sky hemisphere 
and from the sun, 80 per cent is sunlight and 20 per cent skylight. 
Using the curves representing the distribution of energy in radiation 
from sun and sky and combining these in the proportion 80-20 the 
curve B in Fig. 7 is obtained. On a vertical plane exposed to sunhght 
the percentage of skyhght is probably only about 10 per cent, but 
in the shadows a much greater proportion of the radiation is due to 
skylight so that the above ratio (80-20) is thought to represent a 
very probable composition of the average quality of natural illumi- 
nation effective in photography. The curve as plotted shows only 
relative energy values, the maximum ordinate being arbitrarily 
adjusted to unity (1.0). It is not necessary in this case to use absolute 
values since we are interested only in determining the ratio of the 
filter exposure to the no-filter exposure. 

In practical work the only other absorbing material of im- 
portance between the photographic plate and the object is the lens. 
This is usually made of three or more pieces of optical glass which 
may or may not be cemented together with a thin layer of Canada 
balsam. The absorption of energy by this lens in the visible region 
is relatively small and constant but in the ultraviolet, wave-length 
less than 400, the absorption is variable and becomes large as wave- 
length decreases. The lens, therefore, has an appreciable influence 
upon the spectral composition of radiation which reaches the photo- 
graphic material. The spectrophotometric transmission curve of a 
typical motion picture objective is shown in curve C. This curve 
may be represented formally by 


Transactions of S.M.P.E., August 1927 



The ordinate of this curve at any particular wave-length, X, will be 
represented by T\. 

Now the relative intensity of radiation of any particular wave- 
length which reaches the photographic material is proportional to 
the product of the ordinates of the curves B, C, and D. Multiplying 
through at each wave-length and plotting the result as a function of 







Fig. 8. Curves illustrating the determination of filter factor by integration method. 

wave-length, curve A in Fig. 8 is obtained. The total photographic 
effect produced on the sensitive material is directly proportional to 
the shaded area enclosed between the curve and the X-axis. The 
magnitude of this area, P, can be expressed analytically by the 



The area P as given by equation (17) can be determined by 
mechanical integration using a suitable planimeter. As a matter 
of fact it is necessary to do this since in general it is impossible 
to evaluate analytically equations (14), (15), and (16). By using the 
planimeter the area under curve A shown in Fig. 8 was found to be 

Light Filters — Jones 151 

Now suppose that a filter is to be used and let the transmission 
function of this filter be represented by curve B (Fig. 8), expressed by, 

r'=/(x) (18) 

the ordinate of which at any wave-length, X, is T\. By multiplying 
ordinates of curve A by those of curve B at corresponding wave- 
lengths the spectral distribution of the energy reaching the photo- 
graphic plate when the filter is used can be obtained. Curve C at the 
top of Fig. 8 was obtained in this manner. The ordinate of this 
curve at any wave-length, X, is 

T \=JxA\T\T \. 

The total photographic effect produced on the sensitive material 
is directly proportional to the area enclosed under curve C, this 
being represented by the shaded area in the figure. This area, Q, 
is represented analytically by the expression 


By using the planimeter the magnitude of this area can be determined. 
In this case Q was found to be 0.23 X a 

Now the filter factor is given by the ratio of P, the area enclosed by 
curve A, to Q, the area enclosed by curve C. Expressed formally 
this is 

F= — 






Inserting in this the values of P and Q which we have obtained by 
use of the planimeter it is found that 


F = - = 3.3. 


The treatment of this method of computing the filter factor 
involving a consideration of the spectral distribution of energy 
in the illuminant, spectral sensitivity of the material, and spectral 
transmission of the filter, illustrates forcibly the dependence of the 
filter factor upon existing conditions. It is obvious from an exami- 


Transactions of S.M.P.E,, August 1927 

nation of Fig. 7 if curve B, which represents the distribution of energy 
in daylight, be replaced by the curve representing the distribution of 
energy in some other source, such as the tungsten incandescent 
lamp, that curve A would have a very different form. The maximum 
will be at a much greater wave-length and all of the ordinates in 
the region between 500 and 700 m/x will be appreciably greater than 
in case of curve A. It is also evident that by multiplying the ordinates 
of curve B by this new curve, which we may refer to as A'^ the curve 







/ / 




/ P' 


/ B 




/, , , 











Fig. 9. D-log E characteristic curves of photographic material illustrating 
dependence of gamma on wave-length. 

C thus established will enclose a much greater area than the curve 
shown (C) . The ratio of the areas enclosed under these new curves, 
A' and C, therefore will be appreciably less than obtained for the 
daylight illumination condition. Therefore for a yellow filter such 
as is represented by the curve B the multiplying factor when used on 
panchromatic motion picture negative film in tungsten illumination 
will be appreciably less than under conditions of daylight illumination. 
As stated previously this method of treatment is particularly 
adapted to an understanding of why the filter factor depends upon 
the light source and photographic material. In practice filter factors 
are determined in a very different manner by a direct sensitometric 
method. It may be well to discuss this briefly since it will also illus- 

Light Filters — Jones 153 

trate one other condition which must be considered in the specifi- 
cation of a filter factor. 

The density-log exposure characteristic, frequently referred 
to as the Hurter and Driffield (H & D) curve, is obtained by exposing 
a sample of the photographic material in a suitable sensitometer, 
developing, measuring the density of the resulting silver deposits, 
and plotting these densities as a function of log exposure. The 
multiplying factor of a filter may be obtained by making two such 
sensitometric exposures, one with the filter placed between the light 
source and the photographic material and the' other with the filter 
removed. The curves in Fig. 9 illustrate the results obtained in this 
manner, curve A being the density-log E characteristic obtained 
without the filter, and B that with the filter in position. Both curves 
are plotted to the same log E scale, the exposure {I.t) values being 
those incident on the photographic material without the filter in 
position. It is customary in sensitometry to illuminate the photo- 
graphic material with fight equivalent in spectral composition to 
noon sunlight, this being at present the most satisfactory specification 
of standard white light. Curve A therefore gives the effective charac- 
teristic of the material when used in the camera for reproduction of a 
neutral tone series extending from black through the gray series to 
white. Curve A is called the white light characteristic. Curve B 
was obtained by exposing through a deep red filter and is called the 
red characteristic. The exposed films from which these two curves 
were obtained were developed together under exactly the same 
conditions as regards development time and concentration of de- 
veloper. It will be noted that the slope of the straight line portion, 
which is expressed in terms of gamma {y = tan a), oi B is appreciably 
greater than that of A . This indicates that the contrast (7) to which 
a photographic material develops under fixed conditions is not in 
general independent of the wave-length of radiation to which it is 
exposed. In the case of panchromatic materials the contrast resulting 
from exposure through a blue, green, and red filter may or may not be 
different from that obtained by exposure without a filter. Since 
there is a great preponderance of sensitivity to radiation in the 
wave-length region from 380 to 480 mn, the gamma of the charac- 
teristic curve determined from exposures made through the blue 
filter is in general almost identical to that of the white light curve, 
although the blue gamma may frequently be somewhat less (5 or 10 
per cent) than that obtained by exposure to white fight. The green 

154 Transactions of S.M.P.E., August 1927 

gamma is usually somewhat greater than the white Hght gamma. The 
difference is usually found to be of the order of 10 to 15 per cent. 
The red gamma is also on the average greater than the white light 
gamma, by approximately the same amount as that found in the case 
of the green. Furthermore the curves obtained by exposure to 
different qualities of radiation may differ from each other in general 
shape quite apart from the differences in slope already noted. Thus 
the under-exposure region may be shorter and steeper in one case 
than in another and differences in the curvature of the over-exposure 
region may also exist. These differences in shape and slope, resulting 
from variations in the spectral composition of the exposing radiation 
make it difficult to define a standard method for computing filter 

It is customary to express the speed of a photographic material 
in terms of inertia, i, which is defined as the exposure, E, at the 
point where the straight line extended cuts the log E axis, these 
points for the white light (A) and red (B) curves being indicated as 
i and i' respectively. Speed (>S) is inversely proportional to these 
values and hence is defined as, 


S =—k, 

k being constant. Now the multiplying factor may be computed 
from these values of inertia, i, by the expression 

In this case, 

log^ = 0.6, ^ = 4.0 

logi' = 1.6, i' = 40.0. 

ir. = 40/4=10. 

Now a negative made using K = 10 will match in density the no-filter 
negative at some point in the shadow region, but the filter negative 
will have greater density in the half-tone and high-light regions. 

By locating the points p and p' on the two curves where D 
is equal to 2.0 and computing K by using the exposure values corres- 
ponding to these points the filter negative will match the no-filter 
negative in the highlight region but show lower densities in the 
shadow and half-tones. Using this method 

logEiior p) = 2.6, E = 39S. 

Light Filters — Jones 155 

log E (for /) =3. 16, E= 1450. 
irp= 1450/398 = 3.6. 

Likewise balance can be obtained in the half-tone region by- 
using the E values corresponding to points n and n' located on each 
curve where D = 1 .00. 

log £ (for w) = 1.60, £ = 40 
log £ (for ^0 = 2.38, £=240 
ir„ = 240/40 = 6.0. 

Because of limitations in illumination, object brightness, permissible 
exposure time, etc., it is frequently necessary to utilize the under- 
exposure region of the characteristic curve. The expression of plate 
speed^ in terms of the exposure required to produce some limiting 
minimum gradient, dD/d log E, seems in many respects to be a more 
logical procedure than that of using the inertia point. The value of 
minimum gradient adopted for this purpose must be determined from 
a consideration of tone reproduction requirements. The points 
m and m'. Fig. 9, are located on the characteristic curves where 
dD/d log E is equal to .2, these values being chosen arbitrarily for 
the sake of illustration. The multiplying factor may be computed 
in terms of the exposure values corresponding to the points m, m' and 
the filter negative will then match the no-filter negative in the 
extreme shadow region. 

log £ (form) = 0.04, £ = 2.52 

log£(forw0 = 1.2, £=15.9 

i^« = 15. 92/2.52 = 6. 3. 

The determination of K as illustrated by the curves in Fig. 9 
assumes there is no appreciable failure of the reciprocity law within 
the utilized intensity range. For high speed material, such as Eastman 
panchromatic motion picture negative and the Par and Super-Speed 
orthochromatic motion picture negative materials, this assumption 
is justifiable provided the sensitometric exposures used in determining 
the log E characteristics are made at illumination levels of the same 
order as those which exist in the case of camera exposures. 

It is evident from the discussion that the choice of a method for 
expressing multiplying factor must depend on the requirements of 
the particular problem. It is probable that the use of exposure values 
corresponding to densities of 1.0 (in this case giving K = 6.0) most 

156 Transactions of S.M.P.E., August 1927 

satisfactorily meets the requirements of the great majority of cases 
in motion picture work. This in fact is the method usually adopted 
in the measurement of filter factor. 

The curves in Fig. 9 also illustrate the point mentioned in the 
section dealing with the evaluation of filter factor by the use of the 
spectral sensitivity curve (Fig. 7) of the photographic material. It is 
evident that if spectral sensitivity be expressed in terms of reciprocal 
inertia values that the factor obtained will not be the same as when 
this function is expressed in terms, let us say, of energy per unit area 
required to give a fixed density of unity with normal development, 
white light gamma equal to 0.80. For the purpose of filter factor 
determination by the integration method it is necessary therefore 
to consider carefully the manner in which sensitivity is defined. 
By using sensitivity defined in terms of the reciprocal energy per 
unit area required to give unit density at normal development, the 
value of K for any filter computed by the integration method should 
check closely with Kn measured sensitometrically. 

The case illustrated in Fig. 9 probably over-emphasizes the 
difficulty in the specification of multiplying factor since the curves 
shown represent a rather extreme case of gamma differences. The 
filter used in this case has a very sharp cut narrow transmission band 
which tends to give the maximum gamma difference. In using 
"gradual cut" broad transmission band filters such as are employed 
for obtaining orthochromatic rendering, the gamma differences en- 
countered in using panchromatic motion picture negative film are 
inappreciable from the practical standpoint. Even with the tri-color 
filters, which are sharp cut filters transmitting wave-length bands 
approximately 100 m/^ wide, the variation in gamma obtained with 
panchromatic motion picture negative film is not large for the average 
case. The possibility of variation in slope (7) and shape of the D-log 
E characteristic due to spectral composition of the radiation trans- 
mitted by a filter and the resultant dependence of filter factor upon 
the region (highlight, half-tone, or shadow) in which equality of 
density is required should be understood and recognized by workers 
in the photographic field who wish to realize to the fullest extent the 
possibilities and limitations of the light sensitive material. 

In making a photograph of an object on a specific photographic 
niaterial without a filter let the magnitude of the exposure time, lens 
aperture, and illumination be designated as follows: 

Light Filters — Jones - 157 

fo = exposure time 

>So = area of the lens diaphragm opening 
iVo = illumination incident on the object. 

Let the magnitude of these terms as required for obtaining an equally 
exposed negative when using a filter be ia^ Sa, Na, respectively. Then: 

F = (12) 

to So No 

li So = Sa, SiIldN,=Na, 

^ ^- 

F = —, etc. 


Since the area of the diaphragm opening is directly proportional to 
the square of the stop numbers or diayhragm numbers, f, used in 
marking and setting the iris diaphragm, it follows that 


Hence the value of the stop number may be substituted in (12) if 

The vaHdity of (12), which states that the required compensation 
for the decrease of energy incident on the plate when an absorbing 
filter is used can be obtained by a variation of either t, S, or N, or by 
any combination of these terms depends upon the assumption that 
there is no failure of the reciprocity law within the range of intensities 
concerned. This law states that the photochemical action which 
takes place when radiation acts upon a photographic material is 
directly proportional to the product of radiation intensity, J, by the 
time, t, during which it acts and is independent of the absolute value 
of either factor. It is probable for all conditions involved in motion 
picture work that this assumption is justified and that no error of 
sufficient magnitude to be of practical importance will result from 
the use of equation (12). 

In motion picture work, since it is necessary to take at a fixed 
rate, 16 exposures per second, the t factor of exposure can be con- 
trolled only by variations in the angular opening of the camera 
shutter. In using a filter of relatively high factor, it may be impossible 
to increase t sufficiently. It will be necessary in some cases to increase 
the intensity factor of the exposure. This can be done by increasing 
either S or N, both of which control the intensity factor, I, of ex- 

158 Transactions of S.M.P.E., August 1927 

posure. The application of equation (12) to a specific case may be 
of interest. 

Suppose that with I^ equal to 4000 foot candles, /o equal to 
/:6.3, and t^ equal to 1/64 sec. (this corresponds to a shutter opening 
of 90° at standard taking rate of 16 pictures per second), a normally 
exposed negative is obtained. Suppose further that a filter for which 
/^ = 8 is to be used. Assuming that the lens diaphragm can be opened 
only to/: 4.5 without undue loss of focal depth, let it be required to 
determine how much the illumination on the object must be increased 
or decreased to obtain the same exposure on the negative. 

ta fa" 210 6.32 

— • — = = 2.34X1.96 = 4.57. 

/o /o^ 90 4.52 

Since /^ = 8 it is evident from equation (12) that 


Ia = /o= 1.75X4000= 7000 foot candles. 


If a lens aperture of /:3.5 can be tolerated, 

ta fa'' 6.32 

— •— = 2.34X =7.57 

k fo' 3.52 

la = X 4000 = 4240 foot candles . 


Thus by using the lens operating at /:3.5 and the shutter at 210° 
the "eight times" filter may be used by increasing the illumination 
on the set by approximately 5 per cent. 

It should always be kept in mind that the value of a filter factor 
applying to any light filter is vitally dependent upon the spectral 
sensitivity of a photographic material and upon the quality of the 
light used in illuminating the object. In using filter factors for the 
computation of the exposure required the worker should be sure that 
the value employed applies to the filter as used under the existing 
conditions. The mere expression of the value of filter factor without 
a definite statement as to the photographic material and the quality 
of illumination is quite meaningless. 

Use of Light Filters with Panchromatic Films 

In general a collection of objects which compose a scene to be 
photographed presents to the eye areas which differ in color. In fact 

Light Filters — Jones 159 

it is only by differences in one or more of the three attributes of color 
that objects are distinguishable from each other by the visual process. 
The three attributes of color are brilliance , hue, and saturation. In the 
photographic negative the visual contrast -which is due to a summa- 
tion of differences in one or more of these three attributes can only 
be reproduced by a series of silver deposits which differ from each 
other, so far as the eye is concerned, only in the sensation of brilliance 
which they produce when examined visually. Likewise the positive 
produced from this negative, either by projection on a screen or 
printing on a positive material such as a photographic paper, consists 
simply of areas which differ from each other only in brightness and 
which when observed by the eye produce visual sensations differing 
only in brilliance. Since it is impossible with the present photographic 
process to reproduce all of the attributes of color we are forced to 
attempt the reproduction by means of a single variable those differ- 
ences which in the object may be due to the action of three in- 
dependent variables. In view of this situation it seems most logical 
to consider first how closely the one attribute of color which is 
directly rendered by the photographic process, namely brilliance, can 
be reproduced. 

The ordinary (blue-sensitive) photographic plates and films 
differ so widely from the human eye as regards distribution of sensi- 
tivity throughout the spectrum that it is quite impossible with them 
to even approach satisfactory reproduction of the brilliance factor 
in colored objects. These materials are almost completely insensitive 
to radiation of wave-length longer than 550 m/x. The maximum sensi- 
tivity of the human eye lies at 554 m^. It is evident therefore that 
those colors which appear brightest to the eye will be rendered as 
almost black by these photographic materials. 

Orthochromatic materials, by the addition of dye sensitizers to 
the emulsion, have been rendered sensitive to the green in addition 
to the blue, violet, and ultra-violet. This makes it possible to approach 
more closely a satisfactory reproduction of the brilliance factor by 
using these materials. They have, however, practically no sensitivity 
for wave-length longer than 600 m^i. Now the colors which are 
designated as red, orange, and yellow lie within this region and hence 
even with orthochromatic materials are rendered much darker than 
they appear on the visual tone scale. The entire group of colors 
designated as browns also have dominant wave-lengths within this 
region and when the great predominance of such colors is considered 

160 Transactions of S.M.P.E., August 1927 

it is evident that even orthochromatic materials must fail to render 
the majority of scenes with these colors in their proper tonal (bril- 
liance) relation with respect to the scale of gray (extending from black 
to white through grays of all intensities) and with respect to the 
greens, blues, and violets. 

Panchromatic materials, such as motion picture panchromatic 
negative film, are sensitive to all wave-lengths of visible radiation. 
They still possess, however, a great excess of sensitivity, as shown 
by curve D in Fig. 7, to wave-length shorter than 500 mju and hence 
in general render the blue-greens, blues, and violets much too high 
on the visual tone scale relative to the grays and to the warm colors. 
To obtain correct rendering of the brightness attribute of color it is 
necessary therefore in some way to modify the effective distribution 
of sensitivity in such a way that it will correspond more nearly with 
the visual sensitivity to radiation of different wave-lengths. The 
correct rendering of the brilHance attribute of color is termed ortho- 
chromatic reproduction. As used in this sense orthochromatic (derived 
from Greek roots, ortho — correct, and chromatic — color) has a very 
different meaning than as applied to photographic materials which 
as a matter of fact do not give correct color rendering but only more 
nearly correct than a blue sensitive plate. 

Orthochromatic reproduction may not in all cases give the most 
desirable or even the most correct photographic rendering of visual 
contrast which is dependent upon three factors, brightness contrast, 
hue contrast, and saturation contrast. Orthochromatic reproduction 
which means simply the correct reproduction of brightness distribu- 
tion in the object must, however, be regarded as the general case of 
which the enhancement or depression of certain definite colors above 
or below their normal position in the visual brightness scale must be 
considered as special cases. Certainly a thorough understanding of 
the principles of orthochromatic reproduction is prerequisite to an 
intelligent use of methods for producing distorted brightness repro- 

Orthochromatic Reproduction Theory 

In order to compute the spectrophotometric absorption curve 
of a filter which when used with panchromatic film will give perfect 
orthochromatic reproduction of brightness it is only necessary to 
know the distribution of sensitivity for the photographic material 
in question and the distribution of sensitivity for the eye. These 
functions are shown graphically in Fig. 10, curve C representing the 

Light Filters — Jones 


spectral sensitivity of the photographic material and curve D the 
visibiUty function for the eye. Both of these are plotted with maxi- 
mum ordinate equal to unity. In order to determine the spectro- 
photometric transmission function of the required filter it is only 
necessary to divide the ordinate of the visibility curve at any wave- 
length by the corresponding wave-length of the photographic sensi- 

1.2 I 1 1 1 \ \ \ \ 1 1.2 



' 0.8 


5 0.6 



LJ 0.2 

C D 





0.6 h 











10. Spectrophotometric curves showing spectral distribution of sensitivity , 
A] for panchromatic film, C; for visibility function of the eye, D. 

tivity curve. If T\ represents the transmission of the required filter 
at any wave-length its value is given by 

Proceeding in this manner values were obtained from which the 
curve A, Fig. 11, was plotted, the scale of transmissions being shown 
at the left of the diagram. Converting these values to density by 
the usual relation, D = \ogi/T, the spectrophotometric density 
characteristic of the theoretically perfect filter is shown as curve D. 
The absorption characteristic of the light filter which with a given 
photographic material will produce perfect orthochromatic repro- 
duction is dependent only on the two functions shown in Fig. 10 and 
is independent of the spectral distribution of energy in the Hght source 
illuminating the object. 


Transactions of S.M.P.E., August 1927 

In practice it is found that a filter which produces perfect ortho- 
chromatic rendering is entirely too dense necessitating a prohibitively 
great increase in exposure time. It is customary therefore to com- 
promise and use a filter which produces a satisfactory approach to 
orthochromatic rendering. The filters usually used for this purpose 
absorb the ultra-violet entirely and a portion of the visible spectrum 
in the region between 400 and 480 m/x. The Wratten filters of the 








\ D A 


400 500 








1.0 O 



Fig. 11. Spectrophotometric density, D, and transmission, A, curves of a theo- 
retically perfect orthochromatic filter adjusted to Eastman Panchromatic 
Motion Picture negative film. 

K series represent typical light filters of this type. Of these the K-2 
(Wratten No. 8) absorbs practically everything of wave-length 
shorter than 460 mix. This filter used with panchromatic motion 
picture negative produces an approximation to orthochromatic 
rendering and for most purposes is satisfactory from the practical 

From the theoretical standpoint the same filter (see Fig. 11) 
produces perfect orthochromatic rendering regardless of the spectral 
composition of light illuminating the set. In practice it is customary, 
however, to use a much fighter filter when a set is illuminated by 
radiation in which the longer waves predominate, such for instance 

Light Filters — Jones 163 

as is the case with the hght emitted by tungsten incandescent lamps. 
This can be explained on the basis of our subjective evaluation of 
colors as seen under artificial illuminants. Under such conditions 
red and yellow objects actually appear to the eye much brighter in 
proportion to the gray scale and to the blues and violets than under 
conditions of natural illumination. Subjectively, however, they are 
interpreted as having the tonal value which they would have were 
they illuminated with white light. In using a fighter yellow filter for 
working with tungsten we are therefore approaching to the rendition 
of colored objects on the brightness scale as it would appear to the 
eye if the colors in question were illuminated by white light. 

Distortion of Orthochromatic Reproduction 

Remembering now that the total visual contrast between the 
colors which compose the visual field may be due either to brilliance- 
contrast, hue-contrast, or saturation-contrast, it is evident that one or 
two of these factors may be entirely absent leaving sufficient contrast, 
due to the third factor, so that objects in the field of vision may be 
clearly differentiated from each other. Thus it is quite possible, and 
as a matter of fact this frequently occurs in practice, to have two 
or more colored areas precisely equal in brightness (brilliance- 
contrast equal to zero) but clearly differentiated from each other by 
virtue of either hue-contrast or saturation-contrast or a combination 
of these two factors. Now it may be considered that the primary 
object in making a photograph is to reproduce the visual appearance 
and to show structural details of the material within the visual field. 
It seems therefore that the most satisfactory photographic reproduc- 
tion is one which reproduces as nearly as possible the total visual 
contrast existing between the various elements of the object rather 
than the correct reproduction of a single factor upon which total visual 
contrast depends. If brightness-contrast is absent it is necessary to 
take advantage of the existing hue or saturation-contrast to obtain 
a photographic reproduction containing the contrast essential for 
the rendition of the form and detail in the object. For this purpose 
we have available only, variations of brightness-contrast in the 
negative and hence we must attempt to express by means of this 
single variable those visual contrasts which depend upon three 
independent variables. Hence if two areas in the visual field are equal 
in brightness it is only by destroying this equahty that an existing 
visual contrast due to hue or saturation difference can be made 

164 Transactions of S.M.P.E., August 1927 

manifest in the negative. Distortion of the correct reproduction of 
brightness values therefore is a very real necessity in some cases 
and by the use of light filters practically any desired distortion of this 
brightness scale can be obtained. 

The principles involved in obtaining brightness distortion are 
relatively simple and once understood no difficulty should be en- 
countered in applying them to practical problems. As a convenient 
starting point in this discussion let us assume a light filter and photo- 
graphic material (panchromatic) giving perfect orthochromatic 
rendering. Now it is obvious if it is desired to render by differences 
in negative density two areas of different hues but of equal brightness 
it is only necessary to use an additional light filter which will absorb 
to a greater extent the radiation coming from one of the areas than 
it does that from the other. Furthermore, it is evident that either 
one of the areas can be rendered as lower or higher on the brightness 
scale by a proper choice of the absorbing filter. Light filters for this 
purpose are usually termed contrast filters since they are designed 
to enhance the photographic contrast existing between colored 
objects. The general rules applying to the use of contrast filters for 
the distortion or enhancement of brightness-contrast may be stated 
as follows : 

To render a color at a point on the brightness scale higher (en- 
hanced brightness) than its normal position a light filter which 
selectively transmits radiation of the wave-length corresponding to the 
color must be used. 

To render a color at a point on the brightness scale lower (de- 
pressed brightness) than its normal position a light filter which 
selectively absorbs the radiation of wave-length corresponding to the 
color must be used. 

In Table 1 the application of these two rules is shown. In the 
second column are shown the wave-lengths of radiation corresponding 
to the colors as designated in the first column. In the third column 
are shown the filters which must be used with each color in order to 
produce an enhancement of its visual brightness value. These filters 
are described by giving the color name applying to them and the 
wave-length region in which they are transmitting radiation. In the 
last column of the table are shown the filters which must be used to 
produce a depression of the brightness value of the color as indicated 
in the first column. It will be noted that for enhancement, the color 
of the filter corresponds to the color with which it must be used. 

Light Filters — Jones 165 

while for depression, the color of the filter is complementary to the 
color with which it must be used. 

Filters for the depression or enhancement of brightness, contrast 
filters, must as a rule be fairly "sharp cut" filters in order to produce 
effects of sufficient magnitude. Practically all colored objects met 
with in practice have spectrophotometric reflection characteristics 
of the "gradual cut" broad absorption or reflection band type. The 
spectrophotometric curve of two colors which exhibit marked hue 
contrast, therefore, usually overlap appreciably, that is, each em- 
braces partially the same spectral region. To produce appreciable 
enhancement of depression of one of these with respect to the other 
a filter of rather sharp cut is therefore usually required. 

Direction of distortion. When two areas of equal brightness but 
differing in hue or saturation are to be photographed a decision must 
be made as to which one shall be made darker and which lighter than 
its normal value. It has been found by measurement and observation 
that those colors which reflect radiation in the region 550 to 700 m/x 
have in general higher reflecting powers (for the radiation which they 
reflect) than those which reflect radiation of wave-length shorter 
than 550. The former include those colors described as red, orange, 
yellow, and yellow-green and as a group may be referred to as the 
warm colors. The latter, violet, blue, and blue-green, are called cool 
colors. The non-spectral hues, the purples, reflect both red (600 to 
700 mjLt) and blue-violet (400 to 500 m/x). Those in which red pre- 
dominates, the red-purples, are classed with the warm colors, and in 
general are relatively high in reflecting power. The purples in which 
blue predominates, the blue-purples, are classed with the cool colors 
and tend to have relatively low reflection factor. The best general 
rule to be followed in deciding the direction of distortion is to make 
the warm colors lighter and the cool colors darker than called for by 
orthochromatic rendition. This rule is based on sound psychological 
reasoning. Since the brightest colors of our past experience have 
been almost invariably those which fall in the warm classification, 
and the darker less brilliant ones have been found among the cool 
colors, in the absence of any hue or saturation factor the subconscious 
action of memory or stored sense impression tends toward an inter- 
pretation of the higher brightness as representing a warm color rather 
than the reverse. 

It is interesting to note that the use of ordinary blue sensitive 
or orthochromatic photographic materials produces a distortion of 

166 Transactions of S.M.P.E., August 1927 

brightness reproduction which in many cases may tend to the con- 
servation of the contrast between objects or colors which if rendered 
on panchromatic materials by orthochromatic methods would not 
show adequate contrast. This distortion, however, is in the wrong 
direction and always renders the warm colors as much darker than 
cool ones of equal brightness. There is little doubt that this is un- 
desirable and that the rendition obtained with panchromatic film, 
with properly chosen contrast filters when necessary, will give more 
satisfactory results. 

The photographic worker who has for many years been accus- 
tomed to using orthochromatic film frequently feels when he first 
uses panchromatic materials that it does not give as much contrast 
and may criticize the material as lacking in contrast capacity. 
Measurements show that panchromatic film exposed either in the 
sensitometer or in a camera to a neutral gray scale gives a D-log 
E characteristic having a slope, 7, fully as great as the Par-Speed 
or Super-Speed orthochromatic film. It is probable that the worker 
being accustomed to seeing all reds and yellows rendered as unduly 
dark has acquired a false conception as to the actual brightness con- 
trast in the original. Hence the rendition obtained with panchro- 
matic film appears to him as lacking in contrast, while as a matter 
of fact it may be much nearer to the true visual contrast of the object 
than that obtained by the distorted rendering given by orthochro- 
matic materials. 

Magnitude of distortion. Another problem which must be con- 
sidered in the distortion of orthochromatic rendering is that dealing 
with the magnitude of brightness distortion required to compensate 
for the absence of hue and saturation contrast in the reproduction. 
The total visual contrast between objects differing in color may be 
expressed formally by the equation 

in which 0^ = total visual contrast 
C6 = brightness contrast 
C/, = hue contrast 
Cs = saturation contrast. 

In the photographic reproduction Ch and Cs are necessarily zero 
and it may be needful to enhance Cb in order to compensate for this 
absence. The sensitivity of the eye to brightness and brightness 
differences has been studied with great care and the formulation of 

Light Filters — Jones 


the requirements for reproducing precisely this factor is relatively 
simple. Unfortunately the hue and saturation characteristics of the 
eye have not been so carefully investigated and these functions for 
the average normal human eye are not at present established with 
certainty. No quantitative data are available which may be used to 
compute just what proportion of the total visual contrast in the case 
of colored objects is due to each of the three components of contrast. 
It is difficult to estimate therefore just how great a distortion from 
correct ortho chromatic reproduction is necessary in any case to repre- 
sent satisfactorily the hue or saturation contrast which may exist 
in the absence of brightness-contrast. However it seems probable 
that the subjective contrast between two colors differing only in hue 
is directly proportional to the number of least perceptible hue steps 
between the wave-lengths of the two hues in question. On the basis 
of this assumption it is evident that a blue and red of equal brightness 
will require a greater separation on the brightness scale to satisfy 
our requirement of contrast in the reproduction than, let us say, a 
red and a green or a red and orange which lie closer to each other on 
the hue scale. The same reasoning is applicable to the magnitude of 
brightness distortion required to compensate for the presence of 
saturation contrast in the absence of either hue or brightness contrast. 

Table 1 


Filter to Enhance 

Filter to Depress 








600 to 700m/i Red 

600 to 700m/x 


600 to 700mM 


500 to 600 


500 to 600 


500 to 600 


400 to 500 


400 to 500 


400 to 500 


500 to 700 


500 to 700 


500 to 700 

Blue-green 400 to 600 


400 to 600 


400 to 600 


400 to 500 


400 to 500 


400 to 500 

600 to 700 

600 to 700 

600 to 700 

1 Loyd A. Jones and J. I. Crabtree. "Panchromatic Negative Film for 
Motion Pictures." Trans. Soc. M. P. Eng. No. 27, 131, 1927. 

2 M. Bouguer. "Essai D'Optique sur la Gradation de la Lumiere." Paris, 

3 M. G. V. Potapenko. J. Russ. Phys. Chem. Soc. 48, 790, 1916. Brit. J. 
Phot. 68, 507, 1921. 

^ A. Von Hiibl. "Die Phot. Lichtfilter," 18. Halle A. S., 1910. 
s S. E. Sheppard. Phot. J. 66, 399, 1926. 

168 Transactions of S.M.P.E,, August 1927 


Mr. Waller: The curve, shown in one of the sUdes, of the 
sensitivity of the panchromatic emulsion does not compare correctly 
with the published wedge spectrograms. Then, in the filter factor, 
the time of exposure and the shutter opening were given as separate 
things; are they not the same? 

Mr. Jones: These spectrograms are made in an instnmient 
using a diffraction grating as a dispersing element so that the dis- 
persion obtained is normal. The light source used is an unscreened 
acetylene burner giving radiation which is relatively strong in the 
longer wave-length region of the visible spectrum. As compared to 
daylight or sunlight the light emitted by this burner is distinctly 
yellow. This predominance of the longer wave-lengths produces an 
apparent enhancement of the red sensitivity as judged directly from 
the spectrograms. As regards the filter factor, the statement was an 
error on my part. The formula contains three factors; ta, representing 
the exposure time which is determined by the shutter opening for 
taking speed (pictures per second), Sa the area of the lens diaphragm, 
and Na the illumination on the object. 

Prof. Wall: I should like to ask whether there is included in 
the paper data as to how the transmissions of filters, as in the Wratten 
Filter booklet, are obtained for each wavelength? This, I think, 
would be generally instructive. 

Mr. Jones : I have included in my paper a very brief description 
of spectrophotometric methods. I did not deal with this subject in 
detail because I feel it is a little out of place in a paper dealing es- 
sentially with the use of light filters in photography. I have not 
included in this paper many data on the absorption characteristics 
of available light filters. These data have already been published 
in various places. For instance Dr. Gage in a paper read before this 
Society some years ago gave complete spectrophotometric absorption 
characteristics for all of the colored glasses manufactured by the 
Corning Glass Company and in a booklet, Wratten Light Filters, 
complete data relative to the spectrophotometric characteristics of 
dyed gelatine filters are given. It seems quite unnecessary to duplicate 
these pubHshed data. I have discussed the subject rather briefly but 
perhaps not at sufficient length to satisfy some readers. I should 
like to explain that when I started to write this paper I planned to 
begin with the fundamentals and develop the subject logically step 
by step from theory to final application. After thirty-five pages of 

Light Filters — Jones 169 

manuscript I decided it was quite impossible to do this in one paper. 
I might add that we have in progress at the present time rather 
extensive experimental work dealing with the purely practical aspects 
of the photography of colored objects. We have prepared a large 
group of color samples and are measuring their visual reflection 
factors by the flicker photometer method and their photographic 
reflection factors by a method of photographic photometry. This is 
being done under various qualities of radiation such as are emitted 
by the sources commonly used in motion picture work and by em- 
ploying photographic materials of different color sensitivity. We have 
chosen for this work colors of the most reproducible and stable 
character so that the studio worker can if he desires prepare duplicate 
panels. The reflection data will then show at once at what point 
on the visual brightness scale any particular color will be rendered. 
Presentation of these data has been reserved for a later paper. 

Mr. Egeler: Do I understand that from available data for a 
given illuminant and panchromatic material we can not tell just 
what amount of energy we should pass to create in a positive the 
same impressions in black and white as our eye gets? If an emulsion 
receives amounts of energy at different wave-lengths in direct 
proportion to the sensibility of the eye at different wave-lengths, 
would we get any impression of differences of color for the different 
parts of the object photographed? 

Mr. Jones: I feel that we can answer the first question in the 
affirmative. It is only recently that we have been able to do this on 
account of the uncertainty on the data of spectral sensitivity of 
photographic materials. We have just recently obtained data of 
this type on motion picture panchromatic film. I used this in com- 
puting the filter factor by the method described in the paper, that 
is by compounding the spectrophotometric characteristics concerned 
and then integrating the area of the resultant curves. Using this 
method we obtained a filter factor of 3.4 and a filter which as used 
in practice is commonly given a multiplying factor of 3. I consider 
this order of checking is quite satisfactory and well within the re- 
quirements of practice. I believe, therefore, that we are now in a 
position to apply these methods and to obtain results which will 
check satisfactorily with direct sensitometric measurements. I did 
not understand Mr. Egeler's second question. 

Mr. Egeler: In our black and white and color work we attempt 
to show the differences in color by differences in the degree of black 

170 Transactions of S.M.P.E., August 1927 

and white, such as brilliance or reflecting power. If we should attempt 
to show with panchromatic film these different colors appearing in 
the object, how can we balance them against gray so that apparently 
we have sensations with regard to color? 

Mr. Jones: In answering this question I should like to refer 
again to the nature of color as perceived by the eye. The total visual 
contrast between two objects depends on three factors: brightness 
difference, hue difference, and saturation difference. Now by using 
a theoretically perfect orthochromatic filter we can reproduce pre- 
cisely on a photographic material that attribute of visual contrast 
which is dependent upon brightness differences. As an illustration 
let us assume that we have a scale of grays running from to 100 
per cent, in reflecting power, and in the same visual field a number 
of variously colored objects. Now we can measure brightness visually 
by means of a flickei* photometer which I beheve is the approved 
method of measuring brightness in the presence of hue differences. 
By using panchromatic film with a perfectly adjusted orthochromatic 
filter we can reproduce photographically the brightness of these 
variously colored objects in their proper position on the visual 
brightness scale as indicated by the flicker photometer values of 
visual brightness. This rendition we refer to as perfect orthochromatic 
rendering. I should like to emphasize that this rendition may not be 
satisfactory in all cases. For instance it is quite possible to have a 
red and green of equal brightness as determined by the flicker 
photometer measurement. These two colors when rendered ortho- 
chromatically will not be differentiated but will appear identical on 
the photographic plate, that is they will be rendered by the same 
density. Such a condition obviously is unsatisfactory and hence it 
may be necessary to wilfully depart from true orthochromatic re- 
production and as I pointed out previously by a proper choice of 
light filters either one of the two colors can be rendered as lighter or 
darker than the other as desired. Our present knowledge of the 
subject is not sufficient to determine how much distortion of the 
correct brightness rendition is required to compensate for a visual 
contrast due to hue or saturation differences. We do know, however, 
in which direction the distortion should be made, when two colors of 
different hue are identical in brightness the warmer of the two should 
be rendered as brighter. This seems to be based on very sound 
theoretical reasons. 

Light Filters — Jones 171 

Mr. Burnap: As I understand it, the Wratten K filter when 
used under dayhght conditions has a factor of about 3 J. If in- 
candescent lamp illumination be used, what factor will the filter have 
in that case? Does the filter factor vary with the spectral energy 
distribution of the light used as a source? Sunlight and incandescent 
lamps are quite different ; how does this affect the filter? 

Mr. Jones: The quality of the light source does not have 
anything to do with the absorption characteristics of the filter re- 
quired to give orthochromatic rendering. This is a point to which 
I have given much thought. The absorption ' characteristics of a 
filter to give orthochromatic rendering depends only on the spectral 
sensitivity of a photographic material and the sensitivity of the eye 
to radiation of various wave-lengths. It is independent of the light 
source used. Now this seems contradictory to what we actually do in 
practice since it would require that we use the same filter when working 
under tungsten light as we do when working outdoors under daylight 
illumination. As a matter of fact we do not do this but use a much 
lighter filter when working under tungsten illumination. In working 
under tungsten illumination for instance we use a filter which makes 
the colors of colored objects look as they should look if illuminated 
by daylight. This may sound somewhat impossible but I think it 
can be illustrated by considering the conditions which exist at present 
in this room illuminated as it is by tungsten lamps. The sheet of 
white paper which I hold before me I interpret as true white. As a 
matter of fact if its present appearance could be compared with its 
appearance under daylight illumination it would be appreciably 
yellow. I know by experience, however, that the paper is practically 
non-selective in absorbing characteristics. I therefore interpret its 
present appearance under the tungsten lamp as a true white or hueless 
color. In doing this I am influenced by knowledge gained by past 
experience. Similarly it seems that our requirement for the rendition 
of color objects when illuminated by artificial sources is that they 
shall be rendered on the visual tone scale in the positions which they 
would occupy were they illuminated by white light. At any rate in 
practice a lighter filter is always used when working under tungsten 
light than when working under daylight in order to obtain a satis- 
factory rendition of brightness. The reason for this procedure must 
lie in our stored visual impressions and in our interpretation of the 
relative value of colored objects in terms of white light even though 
we may be seeing them under illumination of different quality. 

172 Transactions of S.M.P.E., August 1927 

Mr. Burnap: You did not answer what the factor of the new 
filter would be. I think I had in the back of my mind that we think 
of things in daylight. 

Mr. Jones: A filter, such as the Wratten K-2, which has a 
filter factor of approximately 3, when used with panchromatic film 
under dayhght illumination, will have a factor appreciably less 
when used under tungsten. The factor under tungsten would be 
approximately 2.0. I should like to point out again, however, that 
the use of such a filter under tungsten illumination will produce a 
rendition which we consider as over-corrected. As a matter of fact 
when working under tungsten illumination a very light yellow filter, 
such as K-1, or even no filter at all gives the most satisfactory 
brightness rendition of colored objects. 

Mr. Palmer : I should like to ask Mr. Jones to answer a question 
I answered for Mr. Burnap, concerning the high intensity arc as a 
source of illumination instead of an incandescent lamp. 

Mr. Jones: Judging from what I know of the spectral distri- 
bution of energy in the radiation of the high intensity arc I believe 
that for all practical purposes the same filter will be satisfactory as is 
used for dayhght work. The Wratten filter K-2 should give fairly 
satisfactory orthochromatic rendering with the high intensity arc. 
By this I do not mean theoretically perfect orthochromatic rendering 
but a rendering which should be acceptable. As I pointed out before 
it is necessary to compromise to some extent since a perfect ortho- 
chromatic filter requires a rather great increase in exposure. It is 
apparent from a consideration of the computed curve that a perfect 
orthochromatic filter must absorb some in the extreme red. The 
absence of such absorption, however, is not serious except where the 
requirements are very severe. So far as can be judged by a visual 
inspection of the print the K-2 filter produces satisfactory results. 

Mr. Mayer: This may seem to be irrelevant to the subject, but 
is it not a fact that the cutting off is not constant? Is there not a 
varying degree of rendition of the waves around 3600? 

Mr. Jones: There is undoubtedly a difference in lenses, which 
I think is negligible compared with the cut-off of the K-2 filter, which 
cuts sharply at 440, which is so far in that the lens differences are 
.neghgible. Working without a filter, then, we might find differences 
in lenses which would be appreciable, but for orthochromatic ren- 
dering and the filter value given to you it is negligible. 

Light Filters — Jones 173 

Me. Waller: I want to rise to a point of protest against Mr. 
Jones' statement of the fact that in order to correct for hue we should 
increase brightness as we get into the reds. I don't doubt that Mr. 
Jones' findings are correct scientifically; in fact, I know that they 
are, but another factor enters in which I think we should reason. 
All of us have a store of visual impressions, and as we have stored 
visual impressions, we have stored photographic impressions. Mr. 
Jones just pointed out that it is an accumulation of these impressions 
which makes us see the things in this room as we would see them in 
white fight. Since the time of Daguerre, we have known that things 
photograph black, and I think the reaction of the average audience 
is that darker objects are and should be darker on the screen. There 
is a built-up formula in the motion picture audiences' minds that I 
have found in talking to the fans. 

Mr. Jones: I cannot agree with Mr. Waller's point of view. 
I reafize we have been accustomed in photographic work to the 
distorted rendition of brightness w^hich is given by photographic 
materials of the ordinary blue-sensitive type. There is little doubt 
that this distortion is in the opposite direction to that required by 
the great mass of our every-day experiences. I must agree that we 
are accustomed at present to the photographic convention of render- 
ing reds and yellows as black. I do not befieve, however, that there 
is any reason for continuing this practice which is ob\iously contrary 
to the logical requirements. The fact that we have for a long time 
been doing something obviously wrong is not an excuse for con- 
tinuing. Perhaps Mr. Waller is correct in his opinion that we should 
change our photographic conventionalities somewhat gradually but 
I do not feel that our eventual aim should be to produce a rendering 
as constant as possible with the great mass of our \'isual experiences. 
The fact that we have counteracted a bad habit is no particular 
reason why we should not reform. 

Mr. Ross: We have in mind a studio setting wherein a scene 
includes green trees, blue flowers, red cows, etc. Would it not be 
possible, for a given light source to determine the shades of gray 
paint which could supplant these colors wherebj^ when photographed 
without filters their registration on an ordinary negative, without 
the use of one or more filters, would be the same as if the original 
colors had been photographed with panchromatic film and filters? 

Mr. Jones: I had the same brilUant idea a few years ago and 
thought it advisable to discuss it with someone who had experience 

174 Transactions of S.M.P.E. August 1927 

in studio work. I mentioned it to Mr. Palmer and he stated that 
the idea had been tried sometime ago and was a complete failure. 
One of the reasons he mentioned being chiefly responsible for the 
failure was the fact that the players could not work satisfactorily 
in a set painted only in tones of gray. I believe they complained 
that the atmosphere of the set was cold and emotionless. Having 
been accustomed to being surrounded in every-day life with color, 
the absence of color in the motion picture set reacted very unfavorably 
on their ability to play their parts with realism. It seems to me that 
there is some very sound psychology in this reasoning and I am a 
little inclined to doubt the possibility of constructing motion picture 
sets entirely in tones of gray which will be satisfactory from all 

Mr. Stewart: The previous speaker has exactly anticipated 
what I was going to say. Some ten years ago, knowing that there are 
seventy-one distinguishable shades between black and white, I 
suggested to a director at the Vitagraph that only grays should be 
used in a set, and the idea was carried out. We took the shot, and 
of all the miserable things you ever saw, it was that. I do not quite 
agree with what Mr. Jones said that the temperament of the actor 
is affected; for I must tell you, as an actor, that we are almost blind to 
the surroundings when the director is telling us what he wants. 
But it appears that where the light was full on the colors, the grays 
wanted were obtained, but anything out of the full force of the light, 
the grays blurred away and the sense of color was. entirely absent. 

Mr. Waller: I want to go back for a moment. Mr. Jones 
answered me on the photographic rendition. I did not mean that 
we should interpret red as black, but I meant that we had a point 
of argument as to whether we should take a red view and how we 
should vary it. Mr. Jones states it should be lighter. I think the 
transition to the point where it should be lighter should be very slow. 
I think at first it should be darker. 

Mr. Jones: I do not wish to be misunderstood in my position 
on this point. There are of course many reds and yellows which are 
actually darker, that is of lower brightness, than greens. In such 
cases orthochromatic rendering is quite satisfactory. It is only in 
the rather rare cases where identity of brightness occurs between 
-colors differing in hue that it is necessary to decide upon a distortion 
of orthochromatic reproduction. I cannot help but feel in these 
cases it is better to use a filter that will render these reds, yellows, 

Light Filters — Jones 175 

etc., as somewhat lighter than the color which they match in bright- 
ness. As a matter of fact I think the existence of this identity of 
brightness in the case of colors differing in hue occurs relatively 

Mr. Townse^d: Would it not be a good idea to aim to use the 
filter required to render the flesh, eyes and hair of the actors in 
their proper tonal value, and let the red flowers, green leaves, etc., 
take their natural place? I understand this is the method which gives 
the best results in color photography. 

Mr. Jones: The procedure which Mr. Townsend suggests 
would be satisfactory in most cases but I can imagine instances where 
it would be an absolute failure. For instance, suppose the leading 
lady is wearing an especially beautiful example of the dress-makers' 
art. It is quite possible that the beauty of this material depends 
upon a design brought out by a hue difference between colors of 
practically identical visual brightness. Photographed with perfect 
orthochromatic rendering the design would entirely disappear. I 
grant this is an extreme case but it certainly might occur. I per- 
sonally believe that correct orthochromatic rendering in ninety-nine 
per cent of the cases is the best that can be done. The critics of 
orthochromatic rendering of course always pick the ninety-ninth 
case and point out that it is wrong. In these few cases where a 
balance of photographic brightness exists in the presence of hue and 
saturation differences something must be done, but I do feel for the 
great majority of outdoor work that orthochromatic rendering 
usually gives best results. 

Mr. Waller: If they were of identical brightness should we 
over-correct and bring out the red light or use a light filter and make 
the red darker? I don't say that I am convinced of my argument, 
but I think there is a point of discussion. 

Mr. Jones: I agree. 

Mr. Stewart: Whatever can be done by means of filters and 
panchromatic film that will enable blue-eyed actors to let us see 
they have eyes or blond hair must be an advance. We have Mar- 
guerite Marsh and others, who have ashen-gray or blue eyes, and 
on the screen they seem devoid of pupils. If we try to reproduce a 
play such as "Gentlemen prefer Blondes," how can we make the 
blondes look right with strong back fighting, as most of the elec- 
tricians throw a shadow forward? Recently, we were photographing 
some girls, and I told the cameraman: "You have more light at the 

176 Transactions of S.M.P.E., August 1927 

back than in the front." He wouldn't beheve it. I showed him with a 
pencil how the shadow came towards the camera. At the time I 
was making the photographs of paint-makers' charts, I also got a set 
of dyed hair, and had it photographed under the same conditions. 
I only got two colors, the white hair and all others black, because the 
blond color had a decidedly yellow tinge, which of course photo- 
graphed black. 

Mr. Jones: That condition can be met by orthochromatic 
rendering; that is as far as we need to go. We made a little test to 
determine the rendition of blond hair. Miss Hope Hampton was in 
Rochester a short time ago, and the matter of rendition came up. 
We thought it very advantageous to find out if the hair would come 
out fairly light. A short reel was made on panchromatic film under 
tungsten illumination and it was very satisfactory without any filter. 
If you are working under daylight with such cases I think there 
would be satisfactory rendition with a K-2 filter, which is sufficient. 

Mr. Waller: I don't want to talk too much, but a question 
came up about neutral grays being used in studios, and I have 
a little information on its recent use and success. It has been stated 
here that it was given up some years ago. I think many of you have 
seen the German picture, "Metropolis." I met Eric Pommer, when 
he came here for Famous-Players, and I asked him about the painting 
of the sets. All of them and the costumes were done in neutral tones 
of gray, and it is a beautiful piece of work. 

Mr. Ross: I should like to ask if anyone knows if experiments 
have been made with fluorescent material in the hair or on the 
garments for the purpose of establishing tone color. 

Mr. Stewart: The only thing that has been used is aluminum 
and bronze powders; nothing fluorescent. 

Mr. Coffman: One application of the idea of photographing 
neutral grays to produce synthetic color values in the print is being 
regularly made. In the "Synthechrome" process for producing ani- 
mated drawings in color the original drawings are made in black and 
white and shades of gray, and are so photographed as to give color 
separation in the negative. Any color process, either subtractive 
or additive, may be used for producing the prints. On the screen, 
characters which never lived move through surroundings endowed 
with color which never existed save in the mind of the artist. The 
same general method may be used for testing out color camera ideas 
without the necessity for building special cameras. 

Light Filters — Jones 177 

Mr. Ross: I should like to ask Mr. Stewart if the production 
which was a failure, if the grays had been photometrically determined 
before they were painted on the scene. When we speak of grays we 
have in mind there are three classes of gray; that is gray made from 
black and white, battleship gray, which is a mixture of black and 
white color, and slate gray, which is black and white and blue. It 
occurs to us that it might be possible to determine some particular 
shade of grey, which would, when photographed, represent color as 
seen in daylight. 

Mr. Jones: I should hke to point out that my usage of the 
word "gray" refers to a color without hue. There is only one series 
of grays which extend from white to black. None of these show any 
hue. The colors referred to by Mr. Ross are not grays in the true 
sense of the word but are colors in which the saturation factor is low. 
The fact that they differ from each other in any respect other than 
reflecting power means that these colors must have hue and hence 
are not grays. I think in the interest of consistency we should con- 
fine our usage of the word "gray" to the hueless colors. Just so soon 
as a surface shows any selective absorption and requires the usage 
of such words as yellowish or bluish to describe it, it ceases to be 
a gray. 

Mr. Stewart: I preceded my remarks by saying that artists 
have conceded that there are seventy-one grades of gray between 
black and white. The grays that we used were based on the photo- 
graphic reproductions of the color chart that I showed you yesterday. 
A paint maker's catalogue gave us all the colors which we photo- 
graphed; we made no photometric tests of them. 

(The following communications were received subsequent to the meeting at Nor- 
folk, and in view of the lively interest displayed in the subject, are published.) 

Mr. Ross: Mr. Jones, the fact that the use of correlative 
color shades of gray could be employed to substitute for other es- 
tablished colors has been previously conceived by yourself, and the 
fact that Mr. Pommer has stated that the successful picture entitled 
"METROPOLIS"— and produced by the UFA people— was photo- 
graphed in shades of gray, would tend to further convince us that the 
correlative rendering of color on motion picture films and without 
the use of filters, or special films, is practicable. It certainly seems 
to be the ideal way as it permits the photographing of a set with 
ordinary film — as distinguished from panchromatic and without 

178 Transactions of S.M.P.E., August 1927 

the use of filters. This not only avoids the use of terrific light, which 
is costly, and the glare of which is injurious to the eyes of the actors, 
but also avoids the use of a more costly film. 

When we speak of shades of gray, we refer to subdued white, 
the ultimate subduing of which results in black. White light, as 
is well known, is composed of all of the colors of the visible and 
perhaps some of the invisible spectrum and is only distinguished 
as such by the well known sensations on the retina of the eye. For 
the fulfillment of the plan we have proposed — namely, the substi- 
tution of correlative gray shades for the 71 established colors and 
shades mentioned by Mr. Stewart, the question of whether, or not, 
one of the established colors of the visible spectrum predominates is 
iramaterial as far as the establishing of the shade of gray is concerned. 
In fact, we beheve that to successfully produce the correlative 
shade of gray for some colors and shades thereof, it would be necessary 
to employ a preponderance of one or more established colors as 
distinguished from all other colors present other than black and 
white pigments. By correlative shades of gray, we always refer to 
paints, the composite pigments of which, when photographically 
impressed on an ordinary motion picture film, and without use of a 
filter, will produce a negative of substantially the same degree of 
high and low lights as would be produced by a film giving ortho- 
chromatic rendering. 

And now referring again to Mr. Stewart's remarks, we wish 
to apologize for not more clearly stating our question. We appreciate 
there may be 71 colors and shades thereof for which correlative 
shades of gray may be substituted for photographic purposes. The 
obviously very important factor comprises the obtaining of the 
correct shade of gray as a substitution to produce ortho chromatic 
rendering. We can conceive that to produce the required shade of 
gray for an original color or shade thereof it might require the photo- 
graphing of ten or even one hundred shades of gray to satisfy say ten 
persons having normal sight, that the result was the same as if the 
original color or shade had been photographed with the correct filter 
and the use of an ortho chromatic or panchromatic film, light sources 
being considered as equal. In other words, some 7,000 photographic 
tests niight be required to obtain satisfactory correlative shades 
fo gray for the 71 colors and shades of which Mr. Stewart speaks. 
Now, what we wish to determine is, were these 7,000 more or less 

Light Filters — Jones 179 

tests made, and if so, light sources being equal, how could the failures 
he mentions have obtained? 

Mr. V. A. Stewart: The name of the picture referred to by 
Mr. Pommer was "METROPOLIS" which was taken in Germany by 
the UFA people. It was news to me that the sets were painted in 
grays, though perhaps with the use of filters, which we did not have in 
those days, they might secure the effects obtained. In my experi- 
ments of some ten years ago, I was hoping we might have obtained 
some of the third dimension effects that are seen in many titles 
today, but the artist did not catch this spirit and only secured a 
flat, insipid result, not nearly as good as we were getting with my 
three quarter back Ughting as used by Tom Terriss and his camera- 
man, Joe Schelderfer. This form of lighting is very general now. I 
must confess that I now cannot see any reasons why a color cannot 
be reproduced in its correlative shade of gray and get the same results 
as with colored backgrounds. You will remember that I had a paint 
manufacturer's color chart from which I evolved the colors for actors 
to use in their make-up. 

Of course, in having this chart photographed I was careful to 
see that the plate used was coated with the same numbered emulsion 
as that used on the film. Although I furnished all departments with 
copies, yet we had occasion to use a number of trumpets with ban- 
ners hanging thereto on which certain letters spelled out a name. The 
letters were gold and the banners deep purple. I told the cameraman 
they were of the same actinic value. He knew better and the inevi- 
table result of a re-take followed. On another occasion, we were 
doing an episode in which the French thief, Arsene Lupin, wrote 
his name on the wall showing that he had stolen certain valuable 
paintings, and a yellowish chalk was used on a dark grey background 
for the walls. About two days were spent on this scene before it was 
discovered that the actinic value was identical and retakes were 
necessary. Though to the eye the name was outstanding, yet there 
it was lost on the photographic image. 

When we are working indoors, I am inclined to think with j^ou, 
that with people trained to know color values, there should be no 
difficulties in the use of monochromes, but when we are shooting 
out of doors, we have another condition and judging by the camera- 
men's feelings, they seem to want panchromatic, in spite of the extra 
precautions that must be taken in developing. W'hen using this 

180 Transactions of S.M.P.E., August 1927 

film, the actors' make-up should be modified to suit the new actinic 

Referring to your concluding remark, there were no tests made 
as specified by you, for, as you probably know, there were internal 
disruptions at the Vitagraph at this time and I happened to be very' 
close to Stuart Blackton and not all so with A. E. Smith and Blackton 
left the Company. At that time Blackton and I were going to light 
a set with Mazda lamps on my proposal and a lot of preparation 
was done towards this, but of course came to a sudden stoppage when 
he left. 

Mr. Jones: In answer to Mr. Ross I should like to point out 
first of all that panchromatic film is available at the same cost as 
ordinary film so that the use of sets painted in gray offers no advan- 
tage from this standpoint. Moreover the speed of this material is 
practically identical to that of ordinary film and filters which will 
produce very good approximation to orthochromatic rendering are 
available which have relatively low multiplying factors. This is 
especially true in case studio illumination is used which is relatively 
rich in long wave radiation, that is radiation within the region 
from 550 to 700 mu. 

Theoretically it should be perfectly possible to determine the 
reflecting power of a graj^ to correspond to any specified color. This 
reflecting power of course will depend upon the spectral sensitivity 
of the photographic material and the spectral distribution of energy 
in the radiation from the source which is used to illuminate the set. 
Hence any change either in light source or sensiti\dty of the photo- 
graphic material will necessitate the redetermination of the graj^ 
corresponding to a specified color. This might be a rather serious 
inconvenience as considered from the practical standpoint. There 
is one other factor which may be rather troublesome in arriving at a 
satisfactory solution of this problem. This is the intensification of 
saturation and the change of hue which occurs due to multiple 
reflections of light from colored surfaces. For instance let us consider 
a piece of buff colored fabric which as seen from the camera does 
not lie in a single plane but is draped in folds. This occurs in prac- 
tically all cases of materials used for hangings, draperies, dresses, etc. 
[n the folds of such materials the fight is reflected back and forth 
from the fabric surface and the color as seen by the eye may be a 
relatively deep orange as contrasted to a light buff where the surface 
is viewed directly. Now this change in hue and saturation will mean 

Light Filters — Jones ■ 181 

that the color index of that particular area is entirely different than 
at the point where this multiple reflection does not occur. It would 
be impossible, therefore, to state that this particular fabric has any 
definite correlative gray value. 

As I said before it is perfectly possible theoretically to replace 
any color whatsoever with the corresponding gray, but when w^e 
consider the many complications it may be quite prohibitive from 
the practical standpoint. The establishment of the correlative gray 
for any particular color I think can be done by a method somewhat 
more simple and direct than the method suggested by Mr. Ross. 
Measurements of visual brightness made by the flicker photometer 
are perfectly reliable and quite independent of the normalcy of the 
color vision in the observer. To match this it is only necessary to 
make up a gray paint of the same reflecting power. Of course when 
I say gray I mean a color which is both visually and photographically 

I am incHned to believe that the failure to produce a satisfactory 
result by the use of multiple grays as cited by Mr. Stewart is due to 
one or more of the rather obscure factors, among which may be 
mentioned the change of hue and saturation due to multiple re- 
flections, the change in composition of the light as conditioned by 
reflection from and penetration into the shadows, and possible also 
to the Purkinj e effect . 


Hickman Price 

THE subject I will present has to do with the conservation 
activities of the Motion Picture Producers and Distributors of 
America. I don't know how much of an opportunity you gentlemen 
have had to acquaint yourselves with the ways and means Will 
H. Hays has taken to conserve the resources of this industry, with 
which you are so directly allied. 

The conservation work of the Motion Picture Producers and 
Distributors falls naturally under these headings: 

1. New buildings — the replacing of old structures with modern, 
fireproof buildings ; 

2. Field service — these activities have to do with what are known 
as motion picture exchanges in the United States and Canada; 

3. Relationship with those national bodies that have to do with 
conservation and the making of laws and ordinances that protect 
both the public and the industry; 

4. That field of inquiry and service in which you are somewhat 
concerned — the mechanical aspects of devices having to do with 

Your identity with this industry may date back to the time 
when fires in film-distributing centers were more or less frequent. 
You may have in your files old photographs of buildings which were 
wrecked by fire, of districts in film distributing centers which were 
laid low by flames. If so you will all the more be interested in the 
new building program of the Hays organization. It has resulted 
in the erection during the last four years of two hundred and fifty 
new film exchange quarters. 

In what respects does a motion picture exchange building differ 
primarily from other buildings? The answer is this: Because the 
product handled in these buildings, where it is examined and repaired, 
stored, and from which it is shipped, is highly inflammable, it is 
necessary that these buildings possess a minimum of fire hazards. 

Greatest safety is had by limiting the space in which fiames can 
travel, if once they start. The modern exchange differs from the old 
type of exchange in that fire resistive walls separate the different 


The Conservation Program — Hickman Price 183 

departments. The vaults are separated from an outer passage-way. 
This is separated from the room for receiving and shipping. In turn 
this is separated from the room in which the film is inspected and 
repaired. This department is separated by a fire wall from the front 
part of the establishment in which sales and clerical work are trans- 

Motion picture exchange buildings are built today to put out fires 
before they start, also with the second idea that if fire does start that 
by reason of the separation by fire walls it will be controlled at its 
point of origin. 

In these new buildings fire cannot sweep from one section to 
another. Vertical openings and horizontal openings are all protected. 

A leading authority on fire prevention recently remarked 
that 90 per cent of spreading fires were due to unprotected vertical 
and horizontal openings. These buildings are at all points protected 
and covered. 

Fourteen million dollars have been spent in the last four years in 
the construction of these buildings. The last word in building con- 
struction in this field is the Detroit exchange building, just completed 
at a cost of $1,400,000. 

There are two types of construction of exchange buildings. One 
is built several stories high. The Detroit building is of this character. 
The other type consists of single or two story exchanges built in rows. 
This type is found in Los Angeles, Albany and Memphis. Where 
realty values are not too high, single story buildings are best because 
exit to the street is more convenient. Buildings are in the course of 
construction in Seattle. They are being projected in New York City, 
Philadelphia, New Orleans and Cincinnati. 

The Hays organization has promoted the industry's national 
building program by bringing together the realty owner, the finan- 
ciers, architects and the distributors who lease space in these build- 
ings. So much, briefly, as to the new building program. 

Of the $550,000,000 loss in property destroyed in the United 
States last year by fire virtually none of this loss was sustained in the 
business of film distribution. Partly because of this type of construc- 
tion not one of the 15,000 persons who lost their lives because of fire 
in the United States last year were occupied in the film distributing 

None of the 17,000 people who were injured because of fire in 
this country in this twelve months' period were engaged in this 

184 Transactions of S.M.P.E., August 1927 

business. There are more buildings to be put up, but this is a con- 
structive building policy which is bearing fruit. 

It is desirable that the organization doing this work know at all 
times what the field conditions are in the 644 film distributing 
branches in the United States and Canada. Once each month, 
through the Film Boards of Trade, branch managers composing a 
rotating committee accompanied by the Secretarj^ of the Board make 
an inspection of every exchange in each one of these cities. 

Once every 30 days, six hundred and forty-four reports are 
received in New York from these committees. These reports contain 
thirty -three questions. Every one of them has to be answered. The 
standing of each exchange is determined by the manner in which 
these thirty-three questions are answered. Once every 30 days in the 
Hays Office in New York there meets what is known as the National 
Rating Committee. It is composed of executives of the national 
distributing companies. It checks these six hundred and fortj^-four 
reports. It determines what is known as the National Honor Roll, 
which shows the rating of each of the branches. 

An idea of the far reaching effect of these reports is had when it 
is appreciated that each time the inspection committees visit these 
six hundred and fortj^-four places, they conduct a fire drill. Ever}^ 
one of the several thousand employees participate. They have been 
instructed in their weekly fire drills held at irregular times, how to 
proceed when the fire gong is sounded. 

At present approximately 125,000,000 feet of film are handled 
every day in these film distributing branches. This amounts in 300 
working days to almost fort}^ billion feet. In the term of 4 years it 
means roughly one hundred and fifty billion feet of film have been 
handled by several thousand persons who have received it, inspected 
it, repaired it, stored it, and got it ready again for shipment and made 
that shipment. In this 48 month period this enormous quantity 
of product has been handled with such safety including that part of 
it shipped over the railroads, that the total number of fires due to 
film in this period was only three, two each, with $50.00 damage 
and one with $300.00. 

The progress thus far made as the result of this field service 
speaks for itself in every film distributing center. There is great 
improvement in the morale and spirit of employees. 

Because there is a constant, regrettable change of managers and 
employees it is necessary that this resultful effort of maintaining good 

^^^ Vinn< 

The Conservation Program — Hickman Price 185 

housekeeping be continued indefinitely. In one eastern film distribut- 
ing center there was a complete change of every branch manager in 
six months with one exception. All the general sales managers of 
national distributing companies have changed in the last eighteen 
months. This necessitates educating and training new groups all 
the while. 

Safety education by word of mouth and the printed word pro- 
ceeds continuously. A monthly publication and a series of monthly 
posters are issued. 

Part of the educational program consists of showing a safety 
motion picture film. 

Part of the success that has come in this work has been due to 
the understanding of this whole problem by state and municipal 
officials. They have aided in the adoption of a state model film law. 

As engineers you are interested in conservation. Conservation 
of resources by reducing fire waste, as reflected in lower insurance 
rates, and increased efficiency in this work have been marked. 

Times studies in exchanges caused the method of rotating film 
to be changed in these establishments with marked increased effi- 
ciency. A recent survey developed that 3 minutes were consumed 
in taking an ordinary show of eight reels out of containers and putting 
it into vault cans, and 3 minutes to go through the reverse operation, 
or 6 minutes for each shipment in and out of the exchange. This is 
being eliminated through the use for storage of the same metal 
cases in which film is shipped. Considering that 125,000 reels of 
film are handled every 24 hours, it is clear that in the aggregate an 
enormous saving in time is made in this way. 

A number of technical, mechanical propositions are presented 
to us from time to time. The majority of these we refer to you engi- 
neers as the experts and authorities in your respective fields. A 
device is now under consideration which if it works in practice as 
well as in demonstration will go a long way towards reducing film 
fires in projection booths. 

Through its conservation program the motion picture industry 
is becoming freer and freer of the fire hazards which formerly menaced 

The success of this phase of the Hays organization activities 
is conclusive proof of what can be accomplished in an industry through 
carefully planned and executed trade association organization. 

186 Transactions of S.M.P.E., August 1927 


Mr. Richardson: There are one or two things I should hke to 
call attention to. I do not know how far you go in these matters, but 
within the last few weeks I have had word from places where the 
insurance authorities are sending out inspectors and insisting the 
observation port in the projection room be 6 in. wide by 12 in. high, 
which is placing a handicap on projection, without any beneficial 
results. It is an outrage on the projectionist to compel him to work 
under such conditions, and a gravity operated fire shutter will close 
an opening 12 inches square just as quickly and effectually as it will 
one 6 in. wide by 12 in. high. 

With regard to film inspection, the producer and the exhibitor 
must depend in considerable measure upon the projectionist for the 
excellence or otherwise of what the theater patrons view, and the 
projectionist cannot possibly place a perfect picture upon the screen 
if the film be in poor or bad physical condition. 

I believe I am well within the facts when I say that I receive an 
average of three to four samples of film faults a day, or perhaps twenty 
five each week, which projectionists have cut out of films received 
from exchanges, accompanied by more or less vigorous complaints. 
Much film is still sent to theaters for projection which is in from poor 
to wretched physical condition. 

There is still much complaint from both exchanges and pro- 
jectionists that machine operators (I cannot call them projectionists) 
punch changeover signal holes or affix other markers, near the end 
of reels of film. I would direct your attention, as I have repeatedly 
directed the attention of complaining exchanges, to the fact that this 
pernicious practice can be stopped merely by giving the films a thor- 
ough inspection each time and charging the theater for the footage 
thus ruined. 

Instead of doing this, however, many exchanges affix a marker 
of their own, which is an outrage because it forces the projectionist 
to either omit several feet of each reel or else project to the screen 
the disfiguring marker, which latter real projectionists refuse to do. 
As the projection editor of a paper I receive a vast amount of 
complaints regarding film condition and. could talk on the subject for 
an hour, perhaps interestingly too. Sending out film in other than 
perfect physical condition is hampering the showing of the finished 
product of the industry to the public, and oft times the ''hampering" 
is pretty terrible too. 

The Conservation Program — Hickman Price 187 

Mr. Price: I appreciate this, and if I may, I will answer the 
last question first. I wonder if you happen to recall a paper read 
before this society about 18 months ago by John M. Joy, in which a 
survey conducted by the Motion Picture Producers and Distributors 
was presented. That report set forth conclusively the enormous 
loss that exists today because of film mutilation. Unquestionably, 
there are two sides to the story. The first is the side of the exhibitor 
who through neghgence, carelessness, and inefficiency does not project 
shows with care. This is shown particularly when it comes to the 
change-over markings. Everything from tin foil to chewing gum is 
used with the result that many feet of film often have to be cut out 
when examined at the exchange. Steps have within the last fortnight 
been taken with regard to standardizing the system of change-over 
markings. The other side of the story is that of the distributor. In 
spite of the pains taken some film goes to exhibitors with faulty reels, 
reels not properly wound, and those not inspected with the difigence 
that they should be. I beUeve that steps will soon be taken whereby 
through the instigation of the Producers and Distributors, something 
with regard to the inspection of film and reels causing this loss will be 
brought about. In reply to your first question, I am not fully ac- 
quainted with the subject. 

I am under the impression that the case is in New York state. 
I am glad to know about it and will look into it. 




MOTION picture programs today, especially as found in many 
of the de luxe houses, represent a combination of the earher 
"straight movie" show with a trimming of vaudeville numbers 
formed against a musical background provided by an organ, or- 
chestra, or stage band. 

There are exceptions to this formula, of course, but animate 
performers, assisted by music provided by one or more means, are 
used to supplement the motion pictures which still constitute the 
principal body of the program. 

With the fusion of these two, hitherto widely separated types of 
entertainment, it was only natural that the theatrical atmosphere 
which formed a part of the legitimate stage setting should also be 
used in constructing the modern form of entertainment peculiar to 
the presentation of motion pictures. 

This rather indefinite, almost intangible, "something," usually 
referred to as "atmosphere," is provided for the large part, by means 
of effect lighting. 

In its general aspects, so-called effect lighting is composed of 
three very broad divisions, as follow: 

1. The projection of animated scenic effects; 

2. The projection of color effects; 

3. The projection of simple masks, cut-outs and special lantern 

The last two of the above named divisions are of comparatively 
recent origin, at least as regards the particular manner in which they 
are applied to the presentation of motion pictures. 

Animated scenic effects, however, were used on the legitimate 
stage a score or more years ago and they have been retained, with 
prractically no changes, until the present time. 

* Brenkert Light Projection Company, Detroit, Michigan. 


Effect Lighting in Theaters — Kurlander 


Lighting Effects 
Animated Scenic Effects 
In general, scenic effects are imaged upon a suitable curtain, 
drop, or scrim by the simple expedient of placing a revolving trans- 
parent disc, on which the particular effect is painted, printed, or 

Fig. 1. A typical mica effect disc on which is printed, painted, or photographed, 

the effect scene. 

photographed, before a projection lens, much in the same fashion 
that a slide is projected by a stereopticon lantern. Indeed, many 
of the commonly used effects are nothing more than special, elaborate, 
lantern slides so designed as to repeat themselves continuously upon 
the screen. The driving power for these effects may be obtained from 
either a double-spring clock-work motor or an electric motor, attached 

190 Transactions of S.M.P.E., August 1927 

to the metal casing which encloses the revolving disc for purposes 
of projection and attachment to the projector. 

Mica is used in constructing the discs because it has the ad- 
vantages of light weight; does not readily break; is suitably trans- 
parent; and above all, withstands a high degree of heat. An effect 
disc of the type just described is shown in Fig. 1. In the case of 

Fig. 2. Component parts of a disc ij^Q effect unit. 

certain scenic effects, such as clouds and panoramic \dews of floods 
and cyclones, which are focussed in a fairly sharp manner upon the 
screen, the parts of the effect consist of simply the effect disc, the 
protective casing and the actuating, adjustable speed, clock-work 

Other effects, such as flames, ocean waves, babbling brook, etc., 
use the same parts in their construction with the addition of a 5 in. 
diameter glass ripple plate inserted just in front of the projected 
portion of the disc, so that the projection lens sees the disc through 
the rippled glass. The plate serves to give an irregular f used-motion 
effect to the local areas on the disc which would otherwise move 
across the screen in sharply defined rigid fashion. The component 
parts of an effect unit are shown in Fig. 2. Some effects, as, for 
instance, rain and snow, make use of either a special disc, or a special 

Effect Lighting in Theaters — Kurlander 


plate placed before the disc in such a position that both elements 
are projected at the same time. 

In the case of rain the standard 18 in. mica disc is used, the entire 
disc being opaque with the exception of the rain drops which are 
represented by elongated clear portions of mica for passing the light. 

A rain plate, consisting of two separate plates of either glass or 
mica, on which have been printed closely spaced opaque lines, the 
plates then being placed together and rotated at a sUght angle to 
form a zig-zag pattern, is then placed in front of the rain disc to 
break up the drops and give the effect of a shower. 


Source ^ 

S//Gcf d/sc 

Fig. 3. Optic system used for projecting revolving disc effects. 

A special disc is used in the case of snow, this being of a firm, 
opaque material in which have been punched many small holes 
(representing the snow flakes) closely spaced to simulate either a 
heavy or light snowfall, as desired. 

Each effect disc is provided with a holding plate, the edges of 
which are turned over to form a lip so that the effect casing can be 
slid into a suitable holding plate on the projector in the same fashion 
that a colored gelatine is placed in position in front of a spotlamp. 

These holding plates on the effect casing are not rigidly fastened 
but can be swiveled completely around to permit of the effect casing 
being rotated when in position before the projector condenser lenses. 
In this manner the effect, as shown upon the screen, can be made to 
sweep across it in any desired direction. 

The method of projecting upon the screen such standard effects 
as described above is briefly shown in Fig. 3 where it will be seen that 
the optic system used is that of the well known stereopticon form. 


Transactions of S.M.P.E., August 1927 

Some effects require two elements, one of which consists of a 
suitable lantern slide or a metal stencil-mask placed in the slide 
carrier of the projector. Of such a type is the waving flag effect 
wherein a lantern slide of a flag is projected to the screen through 

Fig. 4. Prism box and metal slide for producing natural colored rainbow effect. 

the slots of a spoked wheel which revolves at a point between the 
projection lens and slide. The wave motion is imparted to the 
flag by the shadows of the wheel spokes sweeping across the projected 
image on the screen. 

Other examples of two-element effects are the rainbow, aurora- 
borealis and lightning effects. The first named, see Fig. 4, uses a 
stencil of a rainbow cut in a metal mask which is then placed in the 
slide-carrier for imaging on the screen, and in front of the projection 

Effect Lighting in Theaters — Kurlander 


lens, Fig. 5, is placed a prism box containing two optical prisms for 

imparting the necessary rainbow colors to the image on the screen. 

Some effects are quite complicated as to structures, a good 

illustration being the moonlight water ripple (a two-element effect 



Fig. 5. Optic system for projecting rainbow effect. 

Fig. 6. Moonlight water ripple box effect and metal ripple mask. 

using a ripple-box and a metal box) shown in Fig. 6. Three ripple 
plates are used in this device, each plate consisting of an opaque 
field across which fine water ripple lines weave so as to overlap and 
form a network. 

These three plates are then caused to move up and down by 
means of a clock-work motor, being thrown out of step (120°) with 

194 Transactions of S.M.P.E., August 1927 

each other by means of three eccentric hubs on the motor shaft; 
each ripple plate being joined to its respective hub through a dri\dng 

There are any number of animated scenic effects which can be 
devised, a few of those more commonly used being Usted in Table 1, 
but in general all of them are operated in one of the ways described 

Scenic lantern slides, in combination with an effect for imparting 
motion to certain areas contained in the picture, are also commonly 
used. Thus, in a slide of a camp-fire group, a flame effect can be 
used to show a realistic camp-fire with, the flames leaping from the 
logs ; or a mountain waterfall can be shown with the water tumbling 
over the brink of the fall to the bottom; or still further, the water 
in the pool at the base of the fall can be made to swirl about. 

Indeed, by means of animated effects, volcanoes can be set into 
action ; the fury of the elements invoked ; and scenes can skip quickly 
from arctic to tropics, from summer to winter — while the patrons sit 
high and dry, in comfortable seats, with their galoshes and umbrellas 
safely parked in the vestibule at home. 

Color Effects 

Color effects, as projected from a special "spot booth" or from 
the projection room proper, are used in prologue work, special num- 
bers, organ solos and even in the showing of motion pictures. 

The principal control, in the case of simple colored lighting 
effects, consists in changing the colors themselves, or in changing 
the shape of the projected floods or spots. 

Thus, a round, square, rectangular, or any odd-shaped colored 
spot or flood may be projected singly or in combination with one or 
more spots or floods of special shape to obtain a blending* or dis- 
solving color action on the stage. 

When the standard double-optic sj^stem type of effect projector 
is used, two different colored beams, of any desired shape, as, for 
instance, square, ma}^ be dissolved back and forth to obtain colors 
other than those represented by the gelatines used in the projectors. 
Or a square flood may be placed around the organ and the organist 
"head-spotted" with either a clear or colored round "spot." Combina- 
tions in this respect are quite numerous. 

* "The use of color for the embellishment of the motion pictm-e program," 
by L. M. Townsend and Loyd A. Jones, Trans. S.M.P.E., Number 21, page 38. 

Effect Lighting in Theaters — Kurlander 


A very pretty effect, and one which is often used in title and 
border work while motion pictures are being shown, is found in the 

Fig. 7. Special color wheel and glass design plates for producing blending colors 


use of special glass design plates which are sharply imaged on the 
screen (or around the picture area) after which a special color wheel, 
consisting of narrow widths of various colored gelatines, is placed 
in front of the projection lens so that the colors, as they pass before 


Transactions of S.M.P.E,, August 1927 

the lens, are caused to weave across the imaged design on the screen; 
a pecuHar blending and fading in-and-out effect being obtained. 

The effect apparatus required to accomplish this is shown in 
Fig. 7. 

As used in connection with film title work, this color effect 
serves as a prelude to the principle title and is operated in the follow- 
ing manner. A blank leader, of a length consistent with the period 
of time it is desired to show the colored effect, is spliced between 
the last reel of one subject and the first reel of the next succeeding 
subject so as to make a complete 2000 ft. reel. 

Fig. 7a. Effect Plates. 

The projectionist, taking a cue from the end of the last reel as it 
passes through the projector, is stationed at the effect projector and 
when the cue is received he gradually opens a pair of vertical framing 
shutters which causes the blending color effect to be seen on the other- 
wise dark screen as if appearing from behind a pair of slowly opening 
draw curtains. 

This effect is allowed to stand on the picture screen while the 
blank leader is being run through the projector and even after the 
title is projected onto the screen, the colored effect then serving as 
an animated field. Just before the picture comes on, the projectionist 
slowly closes the framing shutters, thus making the effect apparently 
disappear behind the closing curtains, leaving the motion pictures 
to follow closely on its heels. 

By means of a special mask, provided for the purpose, the same 
effect can be projected around the border of the motion picture and 
left there until that particular subject is finished; or else a new design 
may be dissolved upon it to take its place, thus constantly changing 
the effect obtained. 

Masks, Cut-outs, and Special Slides 
By far, the greatest number of original effects are obtained by 
the use of simple masks, stencils and, in special instances, lantern 

Effect Lighting in Theaters — Kvrlander 


greatest field and many, indeed, have become quite proficient in this 

Stencils of flowers, ships, hearts, vases, crosses, and many other 
objects are legitimate prey for such effects and are eagerly seized 
upon by projectionists in their quest for the novel and original. 

Fig. 8. Some tj^pical masks, cut-outs and special lantern slides. 

One man in St. Louis has made a stencil of every conceivable kind 
of flower, including a few that possibly never grew; another in Engle- 
wood, N. J., has a penchant for ships and on the slightest provocation 
will project a figure of a vessel of some kind upon the titles of all 
marine films. 

Coming still closer to home, one of our own projectionist- 
members, will, without warning to anyone, sit down and make a pair 
of lantern shdes consisting of a positive and a negative of some odd 
design and then dissolve them in colors back and forth upon the 

This work is unique and never becomes tiresome except for the 
physical exertion required, since an illustrative point in the current 
feature picture can be made to serve as the subject. 


Transactions of S.M.P.E., August 1927 

Some simple forms of stencils, a positive and a negative lantern 
slide, and a special mask, used in obtaining such effects, are shown 
in Fig. 8. Feature pictures, prologues, skits and special acts may 
serve as the inspiration for projecting novel and original effects. 

Fig. 9. Assembly view of spotlamp effect projector. 

Effect Projectors 
The Spotla^np Effect Projector 
In its simplest form an effect projector is nothing more than a 
spotlamp to which have been added an extra condensing lens for 

Effect Lighting in Theaters — Kurlander 199 

converging the light to make it pass through an effect (attached to 
lens holder plate) and then on to a projection lens (attached, in turn, 
to the effect casing). 

The complete assembly appears as in Fig. 9. A special effect 
holder for projecting two-element effects with such an outfit is shown 
in Fig. 10. 

Fig. 10. A special effect holder for use with two-element effects as projected 
by the spotlamp effect projector. 

This simple devise was designed primarily for use "back-stage" 
where it is particularly effective in that it can readily cover a large 
area on a short projection distance; can be easily moved about; 
occupies little space, and can be stripped of its accessories and im- 
pressed into spotlamp duty when required. 

Its adaptability to short focal length lenses for covering large 
areas at limited distances really acts as a powerful deterrent to its 
use in the projection room where, because of the greatly increased 
projection distance, long focal length lenses are required. There 
are no ordinary means for rigidly supporting such lenses on this unit 
and, indeed, even if there were, the device would be quite cumber- 
some and difficult to handle with ease and rapidity. 

Furthermore, it can project only single effects so that the use of 
double effects would require two such units and two operators. 

Modern practice in motion picture theaters only served to 
accentuate the inconveniences of such limitations and it was early 
realized that for this service a special unit, particularly designed to 

200 Transactions of S.M.P.E., August 1927 

meet the conditions in picture theaters was essential for proper effect 

It is true that efforts were made, and for that matter still are 
being made, to apply the spotlamp effect projector to projection 
room operation but a single demonstration, wherein rain drops appear 
of balloon proportions and snowflakes take on the appearance of a 
bombardment by snowballs, serves to convince the economical 
aspirant of the futility of his efforts. 

The spotlamp type of effect projector, therefore, is definitely 
limited to back-stage service. 

The Standard Double Effect Projector 
The peculiar nature of the motion picture program — peculiar, 
that is, only in that it differs greatly from the heretofore accepted 
form of popular entertainment — revealed the need for a projection 
device especially adapted to producing those lighting effects which 
seem to find ever-increasing favor among theater patrons. 

It was only natural therefore, that such a device, as illustrated 
in Fig. 11, should find a place in projection rooms. This is the now 
accepted standard double effect projector which first made its 
appearance some 4 or 5 years ago. 

The advantages it holds over the spotlamp type of effect pro- 
jector are as listed below: 

1. Higher operating efficiency; 

2. Produces effects which can be obtained by no other means; 

3. Projects dissolving lantern slides; 

4. Greater flexibility in operating; 

5. Requires but one attendant for multiple effects; 

6. Easy to operate. 

Aside from these, there are certain advantages which result from 
its placement in the projection room since in this location it comes 
under the supervision of the projectionist who is, or at least should 
be, more skilled in handling such projection devices, than are other 
employees about the theater. 

Furthermore, the centralization of such projection devices in 
the main projection room places the responsibility for their success- 
ful operation in one person's hands instead of distributing it among 
various persons about the theater. This naturally assists the system- 
atic departmentization of the theater so necessary to efficient opera- 

Effect Lighting in Theaters — Kivrlander 


In its simplest form, the double effect projector is nothing more 
than a dissolving stereopticon to which have been added, see Fig. 11, 
horizontal and vertical framing shutters, iris shutters, dowser 
shutters, a hinged slide carrier for swinging out of the way, effect 

Fig. 11. The standard double effect projector. 

holders, mask holders, extra projection lenses, a means for quickly 
altering vertically the direction of both light beams, and a means for 
quickly tilting or swiveling the entire projection mechanism so as to 
cover any desired portion of the "front of the house." 

For projecting lantern slides, it is operated in the ordinary 
fashion like any other slide projector. 

202 Transactions of S.M.P.E., August 1927 

It can also be used in an emergency, although lacking in inten- 
sity, to project "spots" or floods of special odd shapes by the simple 
expedient of placing a suitable cut-out in the slide carrier, or by ma- 
nipulating the iris shutter. 

As an effect projector, it can produce either single or double 
effects by placing a revolving disc effect unit in one, or both, of the 
holders attached in front of the condenser lenses. 

The upper system in Fig, 11 shows the method of supporting 
such effects in place. 

Blending or dissolving colors, projected to any portion of the 
front of the house, are obtained by placing a suitable color wheel in 
the front effect holder, as illustrated by lower system in Fig. 11. 
Glass design slides, cut-outs, or ordinary lantern slides are placed 
in the standard slide carriers, located in the usual position, before 
the condenser lenses. 

The framing shutters, iris shutters, and special mask holders, 
are attached, in complete assembly, to the front of the lamphouse 
in such a manner as to be between the condensing lenses and the 
standard slide-carrier. 

Control over the area covered by the effects — whether projected 
on the motion picture screen or over the entire stage opening — is 
obtained by means of two projection lenses in each system. These 
lenses, one of which is of short focal length and the other of long focal 
length, are mounted at opposite ends of a lens barrel, see Fig. 11, 
and are pivoted to permit each being quickly swung out of the way 
so that a rapid selection of lens is possible. 

The short focal length lens is for projecting effects over the entire 
stage opening, any desired reductions in size being obtained by means 
of the various shutters provided, or by using a special mask. The 
long focal length lens, nearest the screen, is more commonly referred 
to as the stereopticon lens since it is chosen with a view to projecting 
a picture of the same size as that formed by the motion picture 

The picture size can be varied, of course, by substituting lenses 
of any required focal length, which operation requires but several 

This projector is equipped with either arc lamps or high wattage 
projection type incandescent lamps, whichever may be desired. The 
latter are satisfactory on projection distances up to about 100 ft. 

Effect Lighting in Theaters — Kurlander 


Triple Effect Projectors 
In the same manner that a spotlamp is limited to the showing of 
single effects so, also, is the double effect projector limited to the 
simultaneous projection of two effects. There are occasions where 

Fig. 12. A special triple effect projector. 

the restrictions of the double machine are keenly felt, as, for instance, 
where it is desired to show dissolving slides along with a general 
animated effect. 

204 Transactions of S.M.P.E., August 1927 

Then, too, there are certain effects, such as a volcanic eruption 
where nothing but a triple-optic system device can be used. Such 
occasions, to be sure, are not as numerous as where double effects 
are desired; nevertheless there are times when the lack of these 
facilities is a drawback. 

The triple projector is shown in Fig. 12. It is operated in the 
same fashion as the double type. 

High Intensity Arc Single Effect Projector 

The constantly increasing size of new motion picture theaters 
is making strenuous demands upon all types of projection equipment; 
not alone as regards spotlamps and effect projectors, but also upon 
motion picture projectors. A brighter source of light, the high in- 
tensity arc, has for some time past, been used for motion picture 
projection, but it was only recently that the same source was applied 
to the projection of lighting effects. 

Being an entirely new piece of projection apparatus, the poten- 
tialities of this high intensity effect projector. Fig. 13, have not, as 
yet, been fully uncovered and its principal use, therefore, has been 
confined to producing colored floods, spots and odd-shaped il- 
luminated designs. 

In addition to being able to project single animated effects, color 
effects, and cut-outs, slides and the like, it appears to have unlimited 
possibilities in the way of special effects of a type heretofore im- 
possible of attainment due to the limitation in intensity of illumina- 
tion available for such purposes. 

Its reception by theaters during the brief time in which it has 
been available has been, without exception, most favorable so that 
it seems quite likely that it will find a place in the projection rooms 
of all de luxe houses. 

Briefly, by way of description, it consists of essentially the same 
elements as found on the standard double effect projector in that the 
necessary framing shutters, iris shutters, special mask holders, and 
adjustable slide-carriers are mounted, in one assembly, before the 
condensers of a standard high intensity lamphouse. 

Three, or as many as may be desired, projection lenses of graded 
focal length are used, these lenses being locked in position when once 
tocussed. Each lens is mounted on an adjustable, pivoted arm to 
permit of its being swung to one side when not in use. The adjustment 
consists of a thumbscrew for centering each lens in the optic system. 

Effect Lighting in Theaters — Kurlander 


Should a "soft-focus" effect be desired, each lens can be easily 
and quickly slid on the base tubes to the proper focal position. Means 
are provided for placing an interchangeable assembly consisting of 
a light shield, dowser shutter, and effect holder, before each pro- 
jection lens. 

The entire working mechanism of the projector is carefully 
counter-balanced and can be easily swung from side to side, or tilted 

Fig. 13. The high intensity arc single effect projector. 

up and down. Effects or gelatines can be placed in holders, either in 
front of the condenser lens or in front of the respective projection 

It is true, some difficulty is experienced in preventing the colored 
gelatine, when so placed, from burning up too rapidly, although this 
problem has been solved, after a fashion. Heat resisting colored 
glasses seem to offer the best solution to this problem. 

206 Transactions of S.M.P.E., August 1927 


There is one other method of obtaining animated effects on 
which httle has been said so far; that is, by means of motion picture 
films projected in the ordinary manner, or by rear-end projection 
through a translucent screen as is done in the Roxy theater. 

This would, after all, seem to be the most logical method and 
strangely enough, it has been but little used. Natural scenes, other- 
wise unobtainable, could then be used as the background for pro- 
logues and similar work instead of building up effect scenes by use 
of two or more animated effects. 

The principal objection which, undoubtedly, has acted so far to 
limit this method to strictly special cases, is that it is a more costly 
means of obtaining something, which in the main, can easily be pro- 
duced from the front of the house. Then, too, a certain minimum 
projection distance back stage is required so that most existing 
theaters would have great trouble in applying the method. 

Lastly, strange though it may sound, effects projected by means 
of strip film, "movie" fashion, do not appear to be as realistic as those 
obtained in the usual manner. It would appear, therefore, that this 
method of projection is suited only to the showing of complete natural 
scenes, unattainable by any other means. 

It is quite probable that the "mo^de" method will find more 
extensive application, especially in the new theaters although it is 
quite unlikely that it will seriously encroach upon the now commonly 
accepted method. 

Whatever the outcome, this much seems certain; that effect light- 
ing in motion picture theaters is here to stay and will be even more 
generally applied in the future, since, to use a rather crude analogy, 
it represents the "sauce" which makes the "movie" more palatable 
to the average fan. 

Table I 

Some Commonly Used Animated Effects 

Aurora Borealis, changing color effect. 

Babbling brook. 

BHzzard effect. 

Burning forest, panorama. 

Clouds passing moon, moon stationary. 

Moving fleecy clouds with rising moon. 

Effect Lighting in Theaters — Kurlander 207 

Countr}^ scene, panorama. 

Cyclone effect. 

Cyclone with flying objects. 

Descending clouds for imaginary ascension trip. 

Falling flowers. 

Flying angels. 

Flying birds. 

Flying butterflies. 

Fog effect. 

Flood with floating objects. 

Falhng flags. 

Fire and smoke effect. 


Inferno spectacular effect. 

Lightning effect, three brass slides, used in slide carrier, with lightning 
shutter used in effect holder. 

Moon picture slides, with appearing and disappearing clouds. 

Moonlight water ripple, with metal mask. 

Fast moving dark storm clouds. 

Slow moving fleecy clouds. 

Moving and evening sunset clouds. 

Moving river. 

Midnight sun. 

Ocean waves. 

Rain effect. 

Rainbow prism effect with metal mask. 

Sand storm effect. 

Volcano effect, used on triple dissolving projector or three spot- 
lamps. Eruption, flowing lava, rain of fire and ashes. 

Water fafls effect. 

Automatic revolving color wheel. 

Blending colors effect, with glass design slides. 

Waving American flag effect. 

Flying bluebirds. 

Flying fairies. 

Falling sunbeams. 


By J. W. Coffman* 

MOTION photography had its inception in an effort to solve a 
scientific controversy — for Muybridge made his epoch- 
marking trotting-horse pictures in an effort to determine the nature 
of the horse's leg-movements. It is also true that the pictures were 
made in order to settle a bet — but discussion of that phase of the 
subject must be left to some devotee of Lady Luck who may in the 
future present before this body a learned dissertation upon "Motion 
Pictures as first-aid to the Gambler; or African Golf — in seven parts." 

The research scientist was rather slow to utilize the possibilities 
of this new instrument invented for his use — primarily because the 
motion picture is inherently spectacular, and the true votary of science 
has a great distaste for sensationalism. The scientist's loss proved the 
showman's gain, and the crude and awkward scientific toy of thirty 
years ago has developed into the basis of one of the nation's greatest 

And so, having reached the point where one may retain the vest- 
ments of conservatism and yet make use of the motion picture, the 
research man has taken up this instrument, the value of which he had 
previously largely neglected. 

The growing industry itself had been making demands upon him, 
and leading him to familiarity wdth its technique. The very study of 
the problems of projection led to extension of physiological knowledge 
— the phenomena connected with persistence of vision and with color 
perception are much better understood today because of motion pic- 
ture research. Indirectly, the films have accomplished much for 
photographic and colloid chemistry and for illumination engineering. 
Our own avowed profession of motion picture engineering, difficult 
though it may be of definition, is, of course, wholly the creature of the 
flitting shadows of the screen. 

Used for research in fields of science not directly related to itself, 
the motion picture can accomplish much. In the observation of many 
types of phenomena, apparatus manipulation necessarily occupies a 
large part of the observer's attention. If the motion picture camera is 
substituted for the eye, it makes an accurate and impersonal record 

* Carpenter-Goldman Laboratories, Inc., Long Island City, New York. 


The Motion Picture in Science — Coffman 209 

slides. It is here that the ingenuity of the projectionist finds its 
from which most of the factors of the human equation are eliminated. 
The action may be viewed and interpreted by an unlimited number of 
individuals at their own respective conveniences. And the fact that 
the same action can be viewed repeatedly leads to careful and un- 
hurried observation with concentration impossible to any other 
method . 

The wide range of control of the time factor permits observations 
otherwise impossible. The slowing down or speeding up of movements 
make their analysis possible, induce continuity of thought, and make 
clear the relationship of the various elements to each other. There is no 
great obstacle to the intelligible screen presentation within an equal 
space of time of the breaking of a soap-bubble, the growth of a 
plant from seed to maturity, and the movements of a glacier during a 
period of years. 

This method of research can, of course, be profitably apphed to 
our own problems of sprocket and perforation design. 

The microscopist finds that the motion picture presents his 
world-in-miniature with a vividness unknown to ordinary visual 
observation. And the use of various light filters enables the camera to 
pick up details which would completely escape the eye. You have 
witnessed the remarkable results which may be secured by motion 
photomicrography at very slow camera speed. In what other way 
could the subject be as effectively studied as by motion photomicro- 
graphs of growing colonies of bacilli? 

Typical of recent discoveries through cinematic research is 
Doctor Goodhart's (Columbia University) observation of a rhythmic 
muscular wave during certain movements in neuro-muscular diseases. 
Doctor Lloyd (McGill University) has discovered the mechanics of 
conjugation in the cells of the plant spirogyra largely through motion 
photomicrographic research. There will be shown you presently an 
X-ray motion picture of the stomach which led to important modifi- 
cations in the theory of the peristaltic motions of the stomach. 

This list may be extended indefinitely. The structural engineer 
uses the high-speed camera to determine the nature of stresses and 
strains in building materials — the physicist to determine^the nature 
of electrical discharges — the ballistic engineer to study^the flight 
of projectiles — the physical director to observe muscular co-ordination. 

In the field of education the scientific motion picture has undeni- 
able advantages. The day will come when every theorist and inves- 

210 Transactions of S.M.P.E., August 1927 

tigator will find it practically necessary to present a visualization of 
his theories and discoveries. He will be much the gainer, for visuah- 
zation demands a degree of explicitness not expected of verbal pre- 
sentation. A theory may seem perfectly plausible when expressed in 
words, but picturization is the acid test for plausibility. If you now 
believe that you have mastered perfectly some abstract idea, try^ 
expressing it in visual terms. The chances are that you will find much 
that still needs clarification in your concept. 

Pictures make a direct approach to the understanding, while 
words are mere symbols which must be translated in terms of past 
experience. Many details of a picture may be caught in a single glance, 
while words convey visual impressions only through a laborious pro- 
cess of "building up." 

And so the films fill the need for conveying to the student the 
great body of scientific knowledge which he must have as the back- 
ground for original work. Through the re-creative power of the motion 
picture he may stand in outer space and watch the planets move, or go 
back fifty million years to the days of the dinosaurs. He may watch 
the teeming life of a droplet of pond water, or the first faint beat of an 
embryonic heart. Electrons, atoms, molecules, magnetic lines of 
force and other somewhat abstract entities assume a tangible reality 
when translated into animated drawings. Comphcated machines may 
be shown in cross-section, yet still in operation, and an entire subject 
may be visualized in less time than ordinarily required to set up the 
apparatus for a single experiment. 

The motion picture is our only means of transcending our 
physical hmitations and breaking down the barriers of Space and Time 
— the films are the only ticket necessary to sit among the atoms in the 
theater of the monads, or among the stars in the theater of the 


By F. E. Ives 

THE brief paper which I now submit is supplementary to the one 
which I presented at the last Washington meeting of the Society, 
and is essentially a report of progress. In the former paper I stressed 
the fact that I started out with the idea of producing color motion 
picture films of satisfactory quality on ordinary positive motion 
picture film, and by the simplest and most direct means possible, 
and that I have consistently adhered to this scheme. I have con- 
tinued experiments with a view to further simplification and speed 
of operation. 

One simplification relates to the production of the negatives, 
which have been produced in a double camera with light-splitting 
device utihzing a dichroic reflector to economize light. This involves 
the use of a projection printer or other special differential registering 
printer for making the prints. Automatic registration is desirable, 
and is now provided for by making the negatives in a Bell-Howell pin 
registering camera on two special films run face to face between a 
glass plate and a pressure device. Using a special transparent green 
sensitive film in front, the definition of the back film negative, about 
which I felt a little dubious at the start, is astonishingly good, and 
I have heard no criticism on the score of definition. Of course this 
would not be possible without one excessively fine grained and 
transparent green sensitive film, and correct color selection depends 
upon a special surface dye screening on one of the films. The elimi- 
nation of complicated double image cameras with Hght-splitting 
devices is an important achievement, though less important than the 
simplification and perfection of the color print making process, which 
chiefly determines the commercial value of the process. 

The production of the color prints is now carried out auto- 
matically with processing machinery. The print from the red-record 
negative is developed and blue-toned and the base of the blue-print 
reconverted to silver bromide in one machine. It is well-known 
that the blue-toning process nearly destroys the light sensitiveness 
of the adjacent silver bromide, and that long washing has been 
considered necessary to substantially restore this sensitiveness. 
This slows up the process. In the course of experiments with the 


212 Transactions of S.M.P.E., August 1927 

Fox process in which the second image was produced in an uneven 
residual layer of silver bromide after dissolving out the base of the 
blue-toned print with hypo to prevent its redevelopment along with 
the second image, I made the discovery that a suitable adjustment 
of the hypo treatment had the effect of immediately restoring the 
light sensitiveness of the residual silver bromide, so that washing 
was necessary only to stop the solvent action of the hypo and remove 
most of it from the film. This led me to seek an agent which would 
accomplish this result without having a solvent action on the silver 
bromide, all of which should be retained in the film to insure even 
second prints, I was successful in this undertaking, but I do not 
wish to discuss the theory of the process at this time. 

The first black image is now blue-toned and its base reconverted 
to silver bromide in a single solution, the sensitiveness restored in 
another single solution, and the film dried without any washing 
whatever. The second print, from the green-record negative is then 
made, with automatic registration, developed, fixed, washed, passed 
through a chromic acid-ferricyanide bleach, two dye baths and one 
water bath, dried, and the picture is finished. 

Many people, knowing what perfect results have been obtained 
with a trichromatic subtractive process in still color photography, 
have suggested that color cinematography should also be made 
trichromatic. The combination of a blue-toned image and a red-to- 
yellow dichroic image produces such pictorially satisfactory results 
as to minimize the importance of adding a third image, but I have 
provided for this without unnecessary complication by coupling on a 
second simple camera and light-splitting reflector to make a blue- 
record negative, and making the yellow impression from this negative, 
(U. S. Patents 1,186,000, 1,188,939). I doubt if the added compli- 
cation and cost would be justified for the general run of work. 


Clifton Tuttle* 

THE use of the motion picture camera with the microscope is by 
no means a new thing. The work of Comandon, Chevraton, 
Rosenberger, and others is well enough known so that the advantages 
of this combination need only brief mention. In educational work 
the motion picture offers an unapproachable method of presenting 
microscopic subjects before an audience — a method which is much 
more successful than microscopic projection or demonstration by 
means of the double lens oculars. In research, the motion picture 
camera can often take the place of a trained observer saving him 
many tedious hours over the microscope. In some cases a motion 
picture record offers an improvement over visual study by either 
slowing down or accelerating the action of a microscopic subject. 
It is possible by regulation of taking speed to analyze the mechanism 
of changes which can only be surmised by the visual method of study. 

Bacteriologists, colloid chemists, and other users of the micro- 
scope would have benefited by more extensive use of the motion 
picture camera in the past had it not been for the considerable expense 
of 35 millimeter equipment and the inconvenience which the amateur 
encounters in the processing of 35 millimeter film. The advent of 16 
miUimeter film and the equipment for its use has practically removed 
these difficulties and it only remains to point out means whereby the 
16 millimeter camera and the microscope may be brought together. 

The camera requirements for photomicrographic work may 
briefly be Hsted as follows : 1. The lens should be removable. 2. The 
mechanism should preferably be of the hand driven type in order 
that there may be great flexibility in the control of speed. 3. The 
film plane should be close to the camera front, preferably within 
3 or 4 inches, so that the camera may be brought close to the micro- 
scope. 4. The mechanism must run smoothly and the camera box 
must be rigid in its construction. 

The model A, F 1.9, Cine Kodak was used in the work to be 
described. It is much more adaptable than the model B. In fact 
only one change in the stock camera had to be made. The objective 
must be unscrewed from its mount as the optical system of the 

* Research Laboratory, Eastman Kodak Company. 



Transactions of SM.P.E., August 1927 

microscope is to take its place in projecting the image upon the 
fihn. Certain auxihary equipment is desirable for motion photo- 
micrography: — first, a viewing device which will permit of accurate 
focusing and adjustment of the image within the small picture frame 
of 16 mm. film; second, an automatic exposure device which will 
take pictures at any desired interval . 


Fig. 1. Beam Splitter consisting of two right-angle prisms. 

The design of a viewing device presents some rather interesting 
problems in mechanics, optics, and photography. It is not satisfactory 
to inspect the image as formed on the film. The light whether re- 
flected or transmitted is not of high enough intensity for accurate 
focusing and the intermittency of the shutter is an annoyance. 
There should be a field for visual inspection which will be coincident 
with the film frame as to focus, shape, and size. Some form of beam- 
spHtter then is almost essential, and the most practical is a cube 
made of totally reflecting prisms whose interfaces have been thinly 
silvered by cathode sputtering and subsequently cemented together. 
(See Fig. 1.) Such an arrangement transmits a portion of the Hght, 

Motion Photomicrography — Tutile 215 

reflects a portion, and absorbs only a small fraction. After reflection, 
if the image is brought to a focus at the film plane F there will be 
another similar image at the plane I. FP and IP must be equal 
optical distances. The focusing and positioning of the film image F 
may be accompKshed by inspection of the image /. 

From the point of view of mechanical construction, it is much 
simpler to have the two distances fixed. As the magnification of the 
object slide varies with the distance of the image from the end of the 
microscope, some consideration must be given this point before 
deciding upon a value for this distance. Because of the very small 
size of the 16 mm. frame, it is certainly desirable to keep the magni- 
fication at a minimum in order to include as much of the sHde area 
as possible. 

For photomicrographers who are accustomed to working with 
plates up to 8''X10'' in size, the small image area of the Cine Kodak 
frame must exert a cramping effect upon their generous ideas of 
magnification. Magnifications of 5,000 diameters or more which 
are comimon in still photomicrography will be impractical if one 
wishes to include much object slide area. The criterion of minimum 
magnification will of course be the result obtained in the final screen 
image. The ideal result will be a picture in which all of the detail 
which is resolved by the microscope objective will be distinguishable 
on the screen. 

There are in this connection several points to consider: 1. The 
resolving power of the various objectives to be used; 2. The resolving 
power of the photographic emulsion; 3. The resolving power of the 
eye; 4. The magnification obtainable upon projection of the film. 

Under advantageous conditions of vision, it is possible for the 
eye to distinguish clearly detail which is made up of lines and spaces 
or dots which are separated by 1/5 of a milhmeter. This will be true 
when the object is about 1 foot from the eye. If the eye is 10 feet 
from the screen, the finest detail of the picture will have to be sepa- 
rated by a distance of 2 millimeters or more to be visible. Suppose 
that we are projecting a 16 mm. picture 40 inches wide, we will then 
be magnifying the film about 100 diameters, and we should be able 
to see on the screen the image of detail which is separated by only 
l/50th of a millimeter on the film. 

As a matter of fact we are hardly safe in assuming that such 
fine detail is actually recorded by the film. The photographic image 
is made up of a heterogeneous mass of silver particles and the size 

216 Transactions of S.M.P.E., August 1927 

and distribution of these particles play an important role in deter- 
mining the fineness of detail which the emulsion can distinguish. 
The reversed image of 16 mm. film has a resolving power of about 
50 lines per millimeter when it is properly exposed and processed. 
It is much better, however, not to assume the full value of resolving 
power but to allow a small factor of safety taking 40 fines per milH- 
meter as practical. 

The conclusion is that the magnification by the optical sj^stem 
of the microscope and viewing device should be sufficient to separate 
the finest detail resolved by the objective by at least l/40th of a 
millimeter on the film. Knowing the resolving power of all the 
objectives to be used for a given wave-length of fight, and knowing 
the primary magnification given by each of these objectives at a 
tube length of 160 mm., one can easily compute the required secon- 
dary magnification which must be supplied by the added length of 
the viewing device tube. The results for a typical set of objectives 
can be seen in table 1 . 

Showing the inagnification required to separate the 
resolved detail by 1/ IfOth rnillimeter. 

Table 1 







Tube Length 






160 mm. 

\=500 mfji 



1.9 mm. 



5000 lines/mm. 



3.0 " 




85 ■ 


4.0 " 






8.0 " 






16.0 " 






32.0 " 






For the fist of achromatic objectives a secondary magnification 
of 2.5X suppfied by the optical system connecting the microscope 
with the camera will be sufficient. Similar computation shows 
that it would be sufficient also for most of the apochromatic ob- 
jectives. Practically, a magnification of somewhat less than 2X has 
been found satisfactory since afi of the resolving power of the lower 
power objectives is seldom required. 

A viewing device which fulfills the foregoing requirements is 
illustrated in Fig. 2. It is used without an ocular because the quality 
of the projected image when using any of the standard ocular lenses 
is not good at the required image distance. The secondar>^ magni- 
fication results from the increased distance between microscope and 

Motion Photomicrography — Tuttle 


image plane. The barrel slips into the ocular end of the standard 
microscope. The prism beam-spKtter A transmits about 10 per 
cent of the image Ught and reflects about 85 per cent in the horizontal 
direction. The ^dsual frame F is the same size as the film frame 



Fig. 2. Diagram of microscope adapter for Cine Kodak. 

and both frames are equidistant from the center of the cube when 
the finder is connected to the camera. The image in the frame F is 
inspected by an eye lens D which magnifies it about 8X. Since 
an equivalent effective magnification of the film can be obtained 
upon projection, the detail which is visible in the finder is a fairly 
rehable criterion of the detail which will be distinguishable in the 
finished picture. 

The manner in which the view finder is used with the microscope 
is illustrated in Fig. 3. Means is pro\dded whereby all rigid connection 


Transactions of S.M.P.E., August 1927 

between the camera and microscope may be broken before pictures 
are made so as to avoid the transmission of vibration from the 
camera to the microscope. 

The view finder has proved entirely satisfactory in all cases of 
photomicrography which have so far been encountered. A negative 
achromatic lens replacing the ocular would no doubt have improved 
the optical performance of the objectives at this increased tube 

Fig. 3. Cine Kodak with microscope and adapter in place. 

length by maintaining the sine condition, but actually very httle 
disturbance of definition has been noted. 

In order to utihze all of the advantages offered by motion 
photomicrography in the study of microscopic changes, a device 
by means of which the exposure interval may be regulated is es- 
sential. Practically, the range from two or three times normal 
taking speed to a low rate of one picture every 3 minutes seems to be 
useful. For normal and super-normal taking speeds it is practical 
to crank the camera by hand using either the regular crank or a 
super-speed attachment which is supplied as one of the accessories 
to the model A Cine Kodak. For the sub-normal taking speeds a 
continuous drive mechanism comprising a train of worm gears 

Motion Photomicrography — Tuttle 


operated by an electric motor has proved satisfactory. Such a device 
is very simple in construction and aknost infallible in its operation. 
For reliability, the continuous drive has many advantages over any 
form of intermittent mechanism which the author has tried. There 
are no relays or clock controlled shding contacts to give trouble. 
With the device illustrated in Fig. 4, it is possible to get a range of 

Fig. 4. Continuous Drive unit for Cine Kodak. 

speeds from one picture in 3 minutes to ten or twelve per minute. 
As the Cine Kodak is provided with a 180° non-variable shutter, 
the actual exposure time for a single picture is one-half of the interval. 
At first thought, it would seem that a prolonged exposure of over a 
minute might result in a lack of sharpness due to movement. Actually, 
this is not the case for if the movement is slow enough to require a 
slow taking speed there will not be sufficient movement during the 
required time of exposure to cause any apparent lack of sharpness. 
When pictures are made at slow speeds, the light intensity may be 

220 Transactions of S.M.P.E., August 1927 

reduced to a very low level. This is an advantage when working 
with organisms which might be injured by the intensity of light 
required for short exposure times. 

The optical equipment of the microscope need not be of the very 
best to insure good results. Apochromatic objectives and an aplanatic 
condenser may give slightly better results than the achromat and a 
simple Abbe condenser but for most purposes the cheaper equipment 
serves as well. Bulky and expensive optical bench equipment is not 
at all necessary. If the building in which the apparatus is to be used 
is fairly free from vibration caused by traffic or heavy machinery, 
an ordinary table or bench will serve as a support. For high camera 
speeds it is desirable to set the microscope on a separate table. 
Apparatus* similar to that which has been described may be used 
in almost any laboratory. A small dark room for the development of 
test strips is desirable but the finishing of the film is done by the 
various laboratories of the Eastman Kodak Company. 

It is hardly proper to belittle the difficulties of motion photo- 
micrography. The worker will certainly encounter many troubles 
which he has never met in still photomicrography. Not the least 
of the trials of the cameraman will be the temperamental behavior 
of his subjects. The refusal of a protozoan actor to perform naturally 
under the eye of the camera will at times prove extremely exas- 
perating. The problem of the cameraman is to make conditions as 
comfortable as possible for his actors. In making pictures at normal 
or supernormal speeds and high magnifications, the light-intensity 
required is very high. For opaque subjects or for dark field illumi- 
nation, the intensity of a tungsten source may be insufficient, and 
one must resort to the crater of a carbon arc. Unless such a source 
is screened, the heat radiated to the slide will dry up all liquid 
preparations or kill the organisms. A dilute solution of copper sul- 
fate — enough to tinge the liquid a faint green — in a water cell 1 or 2 
inches thick will reduce the transmission of heat sufficiently for the 
making of short scenes. For slow taking speeds, it is possible to use 
a tungsten source, either the "Point-O-Lite" or the 108 watt, 6-8 volt 
ribbon filament lamp, and to reduce the intensity by the inter- 
position of non-diffusing filters of gelatine between the lamp and 

*.The Bausch and Lomb Optical Company, Rochester, N. Y., are at present 
preparing to manufacture an improved form of the apparatus which will include 
a viewing device, camera stand, and motor-drive with speeds varying from 
16/per sec. to one in 3 minutes. 

Motion Photomicrography — Tidtle 221 

microscope. If it is impossible to get the required intensity for the 
necessary taking rate, it is sometimes possible to slow down the 
action of a microscopic organism to a speed which will permit of 
sub-normal taking rates. The addition of minute amounts of chloro- 
form or a solution of egg white will deter the movement of an or- 

The examples of photomicrography which are contained in the 
reel of film were chosen to illustrate the possibihties of the apparatus. 
In this reel are included some accelerated motion studies of the 
penicillium, sl fungus, and the megatherium bacillus. The amoeba 
was taken at about one-third normal taking speed and the Rotifers 
were made at about twice normal speed. The author wishes to 
express his thanks to Dr. S. Bayne-Jones of the Rochester Medical 
School for his cooperation in the making of several of these pictures. 
Some of the special methods of technique which he has used will be 
described in a forthcoming issue of the Journal of Bacteriology in a 
paper by himseK and the author. 

It seems desirable to add as a supplement to the foregoing 
description a few remarks concerning the use of the standard motion 
picture camera with the microscope. In general the same arguments 
regarding the relation of magnification and resoh^ng power apply 
whether one is using 35 mm. or 16 mm. film. The size of either frame 
is small in comparison to that of usual photomicrographic materials 
and for this reason it is incumbent upon the operator to keep the 
magnification as low as is consistent with visual and photographic 
resolution. In the case of most of motion picture negative materials, 
the resolving power is lower than that of the 16 mm. reversal film. 
It should be assumed that the standard 35 mm. film will not have a 
resolving power much in excess of 30 lines per miUimeter. As a 
consequence the secondary- magnification as given in the last column 
of table 1 should be greater than that computed for 16 mm. film. 

When using short wave-length radiation as in the ultra-micro- 
scope the resohdng power of the objectives is very considerably 
increased and it may be that under these circumstances a greater 
magnification may be desirable. 

In the case of the standard motion picture, there is the possi- 
bility of using panchromatic film which is not at present available 
in the 16 mm. size. Panchromatic materials have proved invaluable 
in stiU photomicrography but it is questionable whether panchro- 

222 Transactions of S.M.P.E., August 1927 

matic film will be as great an advantage in motion pictures since 
most of the photomicrographic subjects are colorless unless stained. 
There are but few living organisms which can be stained without 

For a detailed discussion of the use of the standard motion 
picture equipment with the microscope the reader is referred to 
papers listed in the bibliography. 


Chevraton, L. and Mes, F. M. La Cinematique de la segmentation de I'oeuf 

et la chroDophotographie du development de I'oursin. Compt. rend. 

1J^9, 806. 
CoMANDON, J. Cinematographie a I'ultramicroscope, de microbes vivant et des 

particles mobiles. Compt. rend. 149, 938. 
CoMANDON, J., Levaditi, C. and Muteraiilch, S. Etude de la vie et de la 

croissance des cellules in vitro a I'aide de I'enregistrement cinematographique. 

Compt. rend. Soc. de Biol. 7^, 464. 
CoMANDON, J. & Jolly, J. 1917-18. Etude cinematographique de la division 

cellulaire. J. de Physiol et de Path, gen 17, 573. 
CoMANDON, J. Movements des leucoc\i;es et quelques tactismes etudies a I'aide 

de I'enregistrement cinematographique. Ann. de I'lnst. Pasteur, 34, 1. 
France, Wesley G. Ultramicroscopic Motion Picture Study of the Relation of 

Colloidal Content and Plasticity in Clays. J. Am. Ceram. Soc. 1926, 9, 67. 
Naumann, H. Photomicrographs of Growing Crystals. Phot. Rund. 63, 1926, 

RiKLi, M. New pieces of apparatus for micro-cinematography and Instantaneous 

Photomicrography. Filmtechnik, 1926, 2, 154. 
RosENBERGER, H. Micro Motion Pictures. Sci. Am. March 1927, 166. 
ScHATT, P. Micro-cinematography. Filmtechnik, 1925, 1, 2-36. 
Weiss, M. G. Experiences de chronophotographie microscopique. Compt. 

rend. Soc. de Biol. Paris, 1896, 48, 645. 


Mr. Palmer: My remarks are not in the nature of discussion, 
but I thought I might add something to the paper. We have recently 
been making photomicrographs with an ordinary motion picture 
camera. Of course, w^e did not use a very^ large magnification, but 
the job we had was to photograph a flea, and we built a special lens 
mount which removed the ordinary lens about a foot away from the 
film, and placed the flea within an inch or so of the lens. By such an 
arrangement we were able to get an image of the sitter on the film 
about half an inch in length. The flea was held by a very thin piece 

Motion Photomicrography — Tuttle 223 

of wire, so that he had to stay in front of the lens. We had to use 
very powerful illumination and our rate of mortahty was very high. 

Me. Egeler: I should Kke to ask Mr. Tuttle about the range of 
magnification used on the film. 

Mr. Tuttle: The highest is about 200 times. 

The Penetration of red rays. — S. Harcombe states that in deter- 
mining the spectral distribution of a light-source when projected, 
and this obviously applies also with normal illumination, it has been 
found in the laboratory that three spectral distributions are obtained : 
one in which there is no atmospheric absorption and a second in 
which absorption has taken place over ranges of 2828 and 6760 feet. 
It is thus possible to determine the effect of atmospheric absorption 
on the color distribution in the beam, and also to obtain relative 
values of the transmission for the different wave-lengths. The extreme 
red and extreme blue ends of the visual spectrum are difficult to 
observe, but from 6700 to 4500A, the results obtained are reliable. 
Results so far obtained indicate that in all weather the blue light is 
absorbed more than the green and that there is a variation of ab- 
sorption in the red — that is, in rainy weather the maximum trans- 
mission is about 6300A, while in damp weather the red transmission 
falls relative to the green. General^ speaking, the region with best 
transmission is from 5400 to 6600A (Proc. Opt. Conv. 1926, 1, 388). 
Cf. M. Luckiesh ("Color," 1915, 148). Paterson and Dudding 
(Proc. Phys. Soc. London, 1913, ^, 379) give the following table of 
the effect of absorption of colored lights : 








Further data are given by Luckiesh, loc. cit. 

ective range 

Approx. trans- 


mission co-efficient of 

glass used 

3 -3.5 










2 -2.5 



Wm. V. D. Kelley* . 

FILMS are now being processed by continuous moving systems 
in great quantities. The automatic developing, dyeing, toning 
and imbibition machines are examples. In most of these systems, it is 
desirable to visually examine the work, as it progresses, and while the 

film is wet. This is especially so where coloring or registration of two 
images is concerned, and the operator needs to know if he has made 
any errors in keeping the films in step. Also in a system for applying 
colors, where the amount of color applied is under the control and 
judgment of the operator, he needs to quickly know his results. 

* Kelley Color Films, Inc., Hollywood, Calif. 


Examination of Film — Kelley 


It is customary for the operator to examine the moving wet 
film with a large magnifying glass. This is more or less satisfactory 
if the film is not traveling faster than 3 feet a minute — but when it 
travels at, say, 15 feet a minute, it is impossible to make any careful 

To improve upon the above condition, an intermittent device 
was designed which projects each fourth or eighth frame, and holds 

Fig. 2 
A continuous processing projector 

it still during the time that four or eight frames are passing through 
the balance of the processing. 

Referring to Fig. 1 the film leaves the machine over a positively 
drawn sprocket A, then over an idler B, over a loose pulley C, which is 
mounted on a swinging arm and forms a loop of film of the desired 
length. Now it passes to the 8 picture sprocket D, to pulley E, on arm 
F over the driven sprocket G, and out of the machine. Arm F is 
pivoted at H and is drawn in one direction by coil springs. As the 
sprocket G is constantly driven and at the same speed as A and as D 
is locked by catch /, the loop of film M is taken up, drawing arm F 

226 Transactions of S.M.P.E., August 1927 

with it until the end of the slot J in arm K is reached and the catch 
L is Hfted. Spring S then prevails, pulling the arm F which causes the 
film on sprocket D to spin around one turn or part of turn, depending 
on the number of stop pins on this sprocket. This also removes the 
loop at C which again takes up the stock from the machine A. 

7 is a lamp housing, back of which is a right angle prism to 
direct the light through the film ikf on a line with objective II. 
The picture is projected to mirror III and then to a ground glass IV. 
This glass is shielded and the pictures are viewed in daylight. 

The film is so directed that the celluloid side is towards the light 
J, the film being held taut because of being on a slight curve from D 
to E. No gate or pressure of any sort is used because the film is wet. 
In this machine the surplus liquids are removed at a later stage of the 
travel of the film. 

This device does not produce amotion picture. It does pick out 
each eighth picture, or if two pins are used on the eight picture sproc- 
ket, each fourth picture; holds it still and projects it to almost any 
size wanted for visual examination as to its quality. 

The Universities of Naples and Turin, Italy, have founded 
professional chairs for the technique and chemistry of cine films. 
(Filmtechnik, 1927, 3, 136.) 

Hyper-sensitizing cine film. — MM. Gibory, Bachelet & Berliet 
have used with marked success the following method of hyper- 
sensitizing film: 

Pinachrome, 1 :1000 ale. sol. 15 ccm. 

Pinacyanol, 1 :1000 ale. sol. 8 ccm. 

Methyl alcohol . 40 ccm. 

Distilled water 1000 ccm. 

The film v/as bathed, on silvered frames, for 3 minutes in the dark, 
then washed for 1 minute in running water, immersed in an 8 per 
cent solution of strong ammonia, again washed for 1 minute and 
dried on a drum. Development was effected with glycin after 2 
minutes desensitizing with basic scarlet N. This method was found 
, to more than double the speed of the film and it would keep 2 weeks. 
(La Cinemat. FrauQ.; Filmtechnik, 1927, 3, 148). 


By John Grierson 

In approaching the problem of better pictures, some people are so inclined 
to lose themselves in the possibilities of cinema as an art, that they forget the 
obligations of cinema as a public and popular institution. Others again are so 
abandoned to the doctrine that cinema is an "entertainment business," that they 
fail to insist on the development of the medium and the deepening of the appeal. 
It has seemed to me that I might be able to combine both positions. I begin my 
notes with an analysis of the Hmitations imposed on cinema production by the 
box office, and I proceed then to an indication of some of the greater things that 
might be done within these Hmitations. In this way I hope to avoid the usual 
comment offered by cinema executives: that critics forget the practical side of 
tlie business and ignore public wants. 

The prehminary discussion of pubhc attitudes is based on a perusal of the 
audience reaction data gathered at 485 Fifth Avenue and on the word of managers 
in a thousand and one theaters over the United States. For access to the data 
I am beholden to Mr. Henry L. Salsbury, of Famous Players-Lasky Corporation. 


WHERE any scheme of popular production is concerned, one 
must be prepared to start with the realization that the public 
is the final arbiter of form in matters cinematic. Theoretically and 
ideally, there may be no limits to cinema's powers — in imagery, 
fantasy, pure form, etc., etc. — but practically, the limits are set by 
the actual wants of the masses and the terms of their appreciation 
as these are shown in box office results: that is, in actual attention. 
The problem of cinema is the problem really of how profoundly 
cinema may develop within these terms; and criticism, if it is to have 
any practical bearing on the processes of production, may only 
consider the opportunities of producers, as it is willing to consider 
the practical obligations of producers. 

If considered over a period of years, the popular demand at the 
box office may be seen to run along definite lines, and it can, to a 
certain extent, be articulated — however haphazard and untutored 
it may have at first appeared and however little it has had an op- 
portunity to define its nature in the welter of cheap tricks and scurvy 
titillation of the senses which some movie producers have forced on 
it. I shall not say that infallible laws emerge, a knowledge of which 
will guarantee success at the box office ; but an experience of past box 
office results and audience reactions, and a notion of how the show- 


228 Transactions of S.M.P.E., August 1927 

man's mind has developed within the last twenty years of cinema 
activity, force one to draw certain conclusions as to the spirit in 
which production must be undertaken. 

These conclusions, as I shall submit, leave no room for pessimism. 
The world of popular appeal may seem at first sight a tawdry world 
to live in, but when the whole story is told, it may be discovered to be 
a place where opportunities are splendid and where a showman's 
Hfe need not be undignified. 

It is astonishing how far one or two of the greater producers 
have advanced toward a knowledge of the deeper principles of 
popular appeal. There has been of course no great altruism behind 
their efforts, and the end is as it always was, the greatest possible 
return in terms of cash; but on the one hand, their very worship of 
box office has tended toward a realism in their analysis of accounts, 
and the realism in turn has made them distinguish very clearly be- 
tween the larger and the lesser reactions of the public. As a matter 
of fact, in the maze of circus effects, nothing has been more apparent 
than the incredible miUions which were to be made if cinema could 
get under the skin of its people and touch them deeply; and the 
sleepless nights that producers xiave spent when some enormous 
success like "The Birth of a Nation" or "The Covered Wagon" has 
appeared in the ruck of average returns, represent the dim gropings 
of Barnum for the role of prophet. The term "entertainment-plus" 
is now commonly used among producers to indicate their vague 
realisation of a field of appeal in which cinema, to be really successful 
has also in some way or another to be profound. It records, for all 
who care to believe it, the fact that even among showmen — working 
as showmen will — the commercial appeal makes in the end for the 
recognition of the higher enthusiasms. The simple doctrine of the 
average showman (who calls it "service"), that it pays him to make 
his people "feel good," has its natural corollary that it pays him still 
better to make them "feel great." This, I believe, is the one great 
fact which illumines the present of cinema and gives promise for 
the future. 

One producer^ — Mr. Lasky — has in public utterance given 
especial evidence of a critical understanding of these matters. 
Under Lasky's hands the investigation of the cinema public has 
reached curious dimensions. For years a complete account has been 
kept of box office records and audience reactions on each picture and 
every star. Till lately, the system of inquiry has been organized only 

Better Popular Pictures — Grierson 229 

in the United States, but it will no doubt be gradually extended to 
include other countries as well. Exhibitors all over the country are 
required to send in an account of the effect of each picture : whether 
it "held up" or whether it "let down," whether it started that word 
of mouth advertising which is the magic wand of all cinema miracle, 
or plainly "flopped" : what was said of the star, and whether from the 
new evidence, that entity is waxing or waning, what seems to be 
expected (indeed wanted or needed) of the star, what new faces have 
appealed. The exhibitors' own accounts are taken, and the public's 
reactions as they are gathered by posted questioners or eavesdroppers 
at the exits of a thousand and one theaters. 

Taken over a period of years, on pictures and actors of all sorts, 
and read against the history of box office fluctuations and rising 
and falling reputations, these voluminous records take on a certain 
reasonableness, and become something like a great sociological 
document. As a guide to certain matters of comparative psychology 
the evidence is almost unique. Here one may take a single picture 
and follow its fluctuating fortunes among different types of audience 
and even among different nationalities. The same thing can be done 
with any actor with a specific ap^,. j.1. Or one may take a type, say 
a western type of picture, and follow its fortunes as the mere horse- 
play of the woolly west passes into tales of the pioneers, and begins 
to add to itself the importance and the pride of history. Or one may 
take account of the relative box office values (other things being as 
equal as may be) of mystery drama. South Sea drama, Graustark 
drama, costume and historical drama, sheik and sex drama, or the 
authentic drama of actual scenes and living peoples; and decide 
roughly the relative success of the emphasis on youth or age, realism 
or romance, tragedy or happiness, the primitive and the simple or 
the sophisticated and the complex, on faith or fad, instinct or in- 
tellect, on fulfilment and drama with its roots in the practical or 
fantasy and escape with its roots only in play. 

The secret of the whole matter — I shall develop the notion in a 
moment — is that encouragement, so far as cinema is concerned, pays 
better than education, better than art, better than mere entertain- 
ment, better in fact than anything; — and the "plus" in "entertain- 
ment-plus" conceals the very real demand on the part of the public 
that when it goes to cinema, the needs and desires, dreams and 
ambitions of its daily life, will be engaged and appropriately resolved. 
It seems that what people want more than anything of cinema is 

230 Transactions of S.M.P.E., August 1927 

practical example and a renewal of vitality: they are not at all the 
disinterested spectators of Kant's Aesthetic Judgment, except in the 
broader forms of comedy. All the major failures in cinema can be 
set down to the fact that however successful the pictures in question 
may have been in other directions, they have forgotten this funda- 
mental principle. 

Therein lies (I speak of all production intended for majority 
audiences) cinema's obligations — and also its opportunities. For it 
is clear that if such a relation holds, cinema merely abandons the 
role of art to take on a role even more important. Its creative possi- 
bilities as a guiding force among the needs, desires, and ambitions of 
emergent democracy, are obviously enormous. 

To proceed to the detail of these matters, it is clearer than most 
things that the outcome of a picture must be positive rather than 
negative, that it must concern itself with youth and achievement 
rather than with age and disintegration, with matters that instill 
optimism rather than those that suggest a reason for pessimism. 
Tragedy has failed in cinema as realism has failed. The box offices 
of the cinema world shiver whenever youth and sunshine and en- 
thusiasm and evident triumph fade from the screen. This is abun- 
dantly evident in the box office records of "The Last Laugh," 
''Greed," "Black Stairs," "The Salvation Hunters," "Caligari," and 
a dozen other films of outstanding power. Even where there is no 
great pessimism evident or any emphasis laid on failure, drabness 
of scene is enough to decide the fate of a picture. And even the 
atmosphere of the underworld can be exploited up to a point. 

To this drabness European pictures have been peculiarly liable. 
Their preoccupation with the slums, their harping on poverty, their 
tendency to represent workmen and workgirls in the dismal atmos- 
phere and setting of obvious, conscious, and complacent inferiority, 
their preoccupation with weakness and failure in general, do not 
serve them well in the larger cinema market. They are lacking in 
that spirit of bubbling vigor and unchastened self-confidence which 
it seems the fate peculiar of cinema to supply in this modern world 
and the peculiar achievement of American production (be it ever so 
bad) hardly ever to miss. An American once remarked to me that 
European pictures "don't make you feel any good." This principle I 
believe touches the root of cinema success and accounts for much 
of the failure of European cinema in the past. A recent English 
picture, "Hindle Wakes," though cinematically far above the average, 

Better Popular Pictures — Grierson 231 

may be taken as an illustration. Though the central figure (a young 
and independent girl) might have caught up the enthusiasm for 
youth and independence in which cinema audiences are so rich, she 
fails largely to do this. The issue is slight and not hkely to command 
vital attention, and her youth and independence do not bring her 
to any remarkable goal. She begins as a work girl, she ends without 
a future, and the atmosphere about her carries more than a hint of 
the uncertainty of that everlasting economic uncertainty and petty 
fear which makes English proletarian life so distasteful on the screen. 
The net result in the case of ''Hindle Wakes" is that while as cinemati- 
cally good as, say, "Declasse" or "Manhandled," it is not likely to 
have the effect of these pictures at the international box office. 

In a recent analysis of the trend in production Mr. Lasky 
summed up his view in these words: "The mere entertainment or 
program picture is gone forever: it is not enough that a picture be 
well made: it is not enough that it tell an interesting story or that 
it be acted by a good cast. Every picture should have a basic theme 
or element which will lend itself to exploitation." Lasky was ad- 
dressing the showmen of America and no doubt the word exploitation 
carried visions to many of their minds of tie-ups and trailers, stunts, 
drives, twenty-four sheets and ballyhoo. But Lasky 's reference, I 
know, was quite different. Themes which will lend themselves to 
exploitation are those to which men will more eagerly respond; the 
issues, in a word, which prove more acceptable occasions for drama 
and readier basis for encouragement, because they mean the more 
to the masses of the modern world. 

Production, indeed, is falsely keyed unless it takes continual 
account of average ambitions and average preoccupations. It may 
romance to its heart's content, and indeed it must romance, but the 
roots of its romance must be in the every day. Cinematic romance on 
a swift generalisation must be the romance of fulfilment rather than 
the romance of escape. Graustark dramas, costume dramas, historical 
and bearded dramas are only successful at all where there is a modern 
and democratic motif of Cinderella or third son achievement or a 
scheme of easily comprehensible heroics and romance to relieve 
them. The average cinema mind is not historically disposed: it is 
only practically disposed, and it is not easily moved by descriptions 
and issues of a life which it does not share. Abstract and foreign 
settings, faces, figures, fates, fantasies and fashions not easily identi- 
fiable with its own, are always of doubtful interest. This conclusion, 

232 Transactions of S.M.P.E., August 1927 

which may be read in the fate of "Faust," "Siegfried," and a dozen 
other fikns of removed romance, necessitates a very careful handhng 
of all "foreign" material. 

"Nanook" and "Moana" give further illustration of the general 
principle. Both were in a sense "foreign" films, the one a dramatic 
description of Eskimo life, the other a dramatic description of Samoan 
life, and both were made by the same talented director, Mr. Robert 
Flaherty of the Royal Geographical Society. From any cultivated 
point of view, both were great films and each had its individual 
quality of beauty, yet at the box office "Nanook" was an enormous 
success, "Moana," a failure. The reason is simple. "Nanook" is a 
film of action and struggle : it creates suspense, brings excitement and 
touches those satisfactions which western peoples can understand. 
The storm and stress of blizzard play through it, the threat of star- 
vation and disaster and the bleak shadows of an hostile earth are 
constantly present : the need for effort and the value of courage are 
at the root of it. Indeed no matter how foreign the setting and how 
strange the characters, the issue is a primitive issue found in all 
barbarian states where the struggle for life is arduous and constant: 
the masses of the western world can share it easily. 

"Moana," on the other hand, engages a more subtle issue. In 
Samoa where the film was made, life is bountiful and all the ways 
of men are leisured and pleasant. Men, women and children are born 
with flowers in their ears and carry them till they die ; and so distant 
are effort and force from their ideology that even the vocal struggles 
of Caruso played on a tourist gramophone are considered grotesque 
and comical. The natural relation between the sexes, moreover, 
provides no source for what western people consider romantic ex- 

Indeed to provide that sense of drama for themselves without 
which it seems men cannot live, the Samoans have had to invent it, 
and this is the theme of Mr. Flaherty's picture. They found it in 
the ritual of tattoo, in the self-imposed pain by which each youth 
whose heart is "malosi" or strong achieves manhood and the honor 
of manhood. But this for the more practically preoccupied mind of 
the western world is something incomprehensible, and among 
average audiences the issue is not felt at all deeply. "Moana," for 
all the beauty that it held, hved a precarious and forced existence 
under the box office sub-title, "The Love Life of a South Sea Siren" 
and it has not earned the two hundred thousand dollars it cost. It 

Better Popular Pictures — Grierson 233 

goes with three other Paramount films ("Peter Pan/' "A Kiss for 
Cinderella" and "The Beggar on Horseback") into the list of good 
films which have not the heart of the matter in them. 

The complete failure of fantasy in cinema can of course be set 
down to the same cause. Fantasy may be imaginative and in the last 
sense aesthetic material, but unless it is comic fantasy (a very success- 
ful genre as the Mack Sennett films will testify) it is poor stuff for 
the crowd. The Barrie pictures ("Peter Pan" and "A Kiss for Cinder- 
ella") were high above the average as pictures but they were not 
popular successes. "The Beggar on Horseback," a satirical fantasy 
and one of the finest pieces of work done in America was a complete 
failure; "The Thief of Bagdad" was rather less than a success. It 
is doubtful if "CaHgari" means anything outside the ranks of the 

All attemps at psychological studies, it may be guessed, have 
shared a similar fate. Apart from the fact that the medium cannot 
portray the more subtle continuities of the mind with anything ap- 
proaching ease, and is very liable to lose its visual energies if it 
attempts a syllogism, audiences it seems are too absorbed by the 
objective world and the manipulation of it to be interested in such 
matters. The visible cause must be in adequate and normally sensible 
proportion to the visible effect. Struggle within one's own mind, 
whether the struggle be against complexes or traditions, means little 
or nothing. The average mind is in that sense anything but self- 
conscious. Indeed any struggle with intangibles (even when the 
intangible is personified and called the devil) is a trifle suspect. In 
"The Last Laugh" the motion of an old man's heart breaking because 
he lost a uniform was incomprehensible and the film failed as a 
majority picture. In "The Salvation Hunters" the notion of -a per- 
fectly healthy youth being afflicted for seven reels with an unknown 
fear, was incomprehensible, and the film failed as a majority picture. 
The gradual disintegration of two people in "Greed" was largely 
incomprehensible and entirely distasteful, as a majority theme. 
"Caligari," "New Year's Eve," "The Secrets of the Soul," "The 
Sorrows of Satan," "The Student of Prague," are other films which 
illustrate the principle. A dramatic emphasis on the mental processes 
which determine events, especially when they determine abnormal 
events, does not appear to be of primary interest. 

In short the attitudes of the cinema public in its principle 
manifestations is not an aesthetic one, but a practical one. It is 

234 Transactions of S.M.P.E., August 1927 

absorbed primarily with its own affairs and the issue of them. For 
this reason it is that the love interest is so important on the screen 
and why unless the appeal be especially exciting in other directions 
("Nanook," "Grass," and "Beau Geste") the way of any film which 
dispenses with sex is hazardous. It is for this reason too that courage 
is the most admirable quality on the screen, and why evident struggle 
(to the bewilderment of all Orientals and not a few cloistered west- 
erners) is as essential to the dramatic material as light is to the screen- 
ing of it, and why objective achievement (visible, tangible, and in 
the last instance possessable) is almost a holy requisite. 

At the lowest level these principal interests can be met by sheer 
sensationalism, and sensationalism was the first and most obvious 
one of popular sentiment, as it was of popular journalism. But here 
emerges what may be set down as the second principle of cinema show- 
manship. Pictures may be too sophisticated, too subtle, too foreign, 
and too far-removed from their public, but taken all in all, they can 
never be too big. Once regard is paid to the simples and fundamentals 
of the practical mind, production can be as imaginative as it pleases. 
Better results indeed have come when sex interest has been merged 
in romance and violence in adventure; and the results have been 
better still where the romance has slipped into the confines of poetry 
and the adventure has taken on the size of human significance. 

American films have never done much in the first regard; a,nd 
their interpretation of the love interest remains for the most part 
shallow in the extreme. The relation of its heroes to its heroines is 
as a rule conceived trivially and unimaginatively and the manifesta- 
tion of feeling in the matter is generally obvious and uninspired: 
this despite the medium's immense capacity for visual imagery and 
significant atmosphere. The reasons doubtless can be found in the 
conditions of American life. On the other hand, under box office 
influence such incidental characters, of sex drama, as the vamp and 
the villain, have undergone a change in the direction of subtlety, 
and feminine appeal, if never exactly profound, has come to be 
portrayed in terms of greater naturalness. When, as in "Variety" 
and "The Merry Widow," some cinematic vitahty has been breathed 
into the love motif, or where, as in one or two of the Fairbanks 
pictures, the love story has been set in especially pleasant places, the 
box office effect has been certain. In this matter, however, Americans 
taken all in all, have failed dismally. They seem unable to reheve 
themselves of a concentration on 'le contact de deux epidermes', or 

Better Popular Pictures — Grierson 235 

at least unable to treat it imaginatively, and I believe that if pro- 
duction will carry the love stories of the screen into poetry and 
plausibility, the incomprehensible facility of the movie amour will 
straightway appear at the box office for what it is. 

In the matter of adventure, American producers have shown a 
greater understanding and in this regard they have everything to 
teach the producers of other countries. The field of action first 
exploited by the cowboy pictures has been extended to include the 
exploits of the pioneers and the more picturesque and adventurous 
incidents of history with the consequent deepening of the dramatic 
appeal. The word "epic" has crept into the producer's vocabulary, 
only dimly understood as yet, but indicating a popular form in which 
the exploits of men add to their first primitive interest a direct feeling 
for the sources of national pride and human importance. 

It would of course be easy to overemphasize the intelligence 
of American producers in this respect, and in a recent list of over two 
hundred releases of all kinds, I count eighty-two western pictures 
which make no effort to exploit the deeper strata of adventure. It 
is apparent moreover that any grasp of the principles involved would 
have extended the field of action still further, into the epic affairs of 
industry, the romance of commerce, the trafficking of men around 
the seven seas, the building of cities in the wilderness, and so on. 
At the same time the advance, such as it is, gives an important lead 
to what undoubtedly must prove a most fertile field for cinema mater- 
ial in the future. 

I think of the advance as due almost entirely to the Famous 
Players organization. It made "The Covered Wagon," and realizing 
thereafter that in an art of movement it is as well for the movement 
to be momentous, it followed up with "North of 36," "The Thunder- 
ing Herd," "The Vanishing American," "The Pony Express," "Old 
Ironsides," "Wings," and "The Rough Riders." Other production 
imits have caught the principle and have made or are now making 
pictures dealing with the transcontinental railroad, the United 
States mail, the Panama Canal, the history of the automobile, and 
the exploits of the Hudson's Bay Company. Not all of these have been 
great pictures, but all of them have had the germ of cinema truth 
in them, and all have been box office successes of the first order. 

Greater things still could have been done if the term "epic" had 
not been unnaturally and stupidly associated for so long with "western" 
pictures and if the true field of "epic" adventure had been realized. 

236 Transactions of S.M.P.E., August T927 

More still could have been done if the personal elements in these 
sweeping films had been handled less trivially. The Americans have 
very correctly sold their history with a tale, and invested their scenery 
and action with the charm of a personal romance; but in most cases 
the personal elements have overbalanced the larger theme and 
detracted from its dignity. This is a continuing and seemingly ineradi- 
cable fault. So the action be deeply set and powerfully executed, the 
love interest need not be over-emphasized. "Beau Geste," "Potem- 
kin," "Nanook" and the first part of "The Vanishing American" 
will serve to demonstrate how a film may even dispense with it 
entirely, but in any case, the difficulty could be overcome (and the 
women who make up the larger half of cinema audiences, satisfied) 
by a more subtle use of the medium in the presentation of it. 

The best guide to the nature of cinema's public relations is of 
course the attitude to the central figures revealed in the star system. 
There has been a tendency to deplore the star system, and people 
accustomed to stage conditions are apt to think of star values as 
acting values pure and simple. This comment applies particularly to 
England, from which I write. Both attitudes miss the special signifi- 
cance of the cinema relation. It is perfectly true that some cinema 
figures have been foisted on the public by advertisement, and perfectly 
true that the method of selling pictures (before they are made) on the 
names of the participants, has encouraged a false importance in minor 
personalities; but at the same time, a value attaches to personality 
on the screen which has nothing to do with acting ability ; and in the 
really significant cases, the relation of the star to the pubUc is too 
intimate to be set down to the wiles of advertisement and the ne- 
cessities of salesmanship. 

Two factors combine in the making of cinema stars. In the first 
place the medium makes the portrayal of different characters much 
more difficult and far less attractive than it is on the stage, and lends 
itself rather to one-role actors, or people who are visually interesting 
in themselves, — in a word to personalities. This point I shall take up 
later. In the second place, majority audiences want personalities 
rather than clever actors. They want figures with a continuing fife 
and a continuing role in the world from picture to picture, with whom 
they can identify themselves. The star system is psychologically 
very like a mythological system. It represents a collection of per- 
sonalities who, in cinematic terms, suggest the manners and ways 
to be loved and possessed, or most to be despised and avoided. They 

Better Popular Pictures — Grierson 237 

are in a word the figures who are especially significant of life as it is 
understood, and best fitted as guides to conduct. They are on the 
whole a little higher than the angels, and are rewarded accordingly. 
An analysis of the church's relations to the masses of the modern 
world (while greater education, widening horizons, and greater 
personal ambitions are putting a premium on inspiration and 
example) may indicate the position which cinema with all its faults 
is slowly capturing. 

''The handling of stars," as this art has been developed in Amer- 
ica, involves all those intricate processes which may be cojiceived to 
a.ttend the manipulation of divinities. It involves continual care that 
the company in which the star is seen is fitting, — that the things that 
befall him are fitting (a false step even in fictional life is held against 
him), — that he never suggest his knowledge of ignoble things, play 
an unsympathetic part or in any way destroy the illusion of perfection 
which makes him an example. In his fictional world the star is 
manipulated very much as Machiavelli would have his Prince 
manipulated in the political world; and the principles set down "for 
the conduct of a Prince who would gain renown" are as much the 
source of a star's authority as his cinematic presence and his power 
of expression. The personalities which go furthest are, of course, 
those whose appeal is to the vivid primary interests I have named in 
dealing with themes. For the rest, the public is not unlike Fortune 
in the classical description: 'Tt is better to be adventurous than 
cautious toward her, because Fortune is a woman; and it is seen that 
she allows herself to be mastered by the adventurous rather than by 
those who go more coldly. She is therefore womanlike, a lover of 
young men, because they are less cautious, more violent, and with 
more audacity command her." 

The mistakes of Gloria Swanson in the latter part of her career, 
the ultimate failure of Meighan to hold his worshippers despite their 
deep-rooted loyalty in the past, and the waning of stars like Hart, 
Nazimova, Nita Naldi, and to a certain extent, Pola Negri, illustrate 
one or two of the thousand natural shocks that stars are heir to. 
In some cases failure has been due to decreasing cinematic vitality 
or the passing of an agreeable personal appearance, in other cases to 
disagreeable associations or the effect of roles which detracted from 
their dignity. An ambition to follow the example of stage actors 
and demonstrate versatility has been especially fatal. The cinematic 
career of Pola Negri illustrates the folly of attempting to play in 

238 Transactions of S.M.P.E., August 1927 

sympathetic roles a figure whose natural cinematic character does not 
lend itself to them. In this case excellent acting, heavy advertisement, 
and a choice of stories especially designed to capture the affections 
of the public have hardly succeeded in overcoming the decree of the 

This worship of stars will indicate how much the private fortunes 
of the individual are concerned in average cinema relations. It may 
be that the Russian people are different from others in this respect 
for 'Totemkin" had no central figures. If there were stars in 'To- 
temkin," it was a case of the cruiser co-starring with the mob in 
Odessa. 'Totemkin" however was directly and, I believe, consciously 
inspired by the Communist way of thought, and interest in heroes 
was purposely eliminated in favor of an interest in collective life. 
The film meant the less for that reason at the average box office in 
America and its unprecedented command over speed and action, 
fight, fury, and terrible death, could not overcome the original 
difficulty, that the average spectator of more individualistic cultures 
cannot see himself written in its record. 

"Potemkin," however, illustrates a possible departure from the 
tyranny of individualism. On Broadway where this film ran for a 
couple of months the film inspired more enthusiasm among its ad- 
mirers than any film has ever done before. The spectator, however 
individualistic in his outlook, will dispense temporarily with an 
emphasis on personal fortunes the moment a picture touches the 
sources of his pride. A few appreciated "Potemkin" critically for its 
cinematic values but the general audiences which cheered their way 
through the film did so for the revolutionary cause it espoused and 
the pride of class to which it appealed. 

I can think of no other similar case (the American producers have 
always been careful to personify their patriotic issues), but I can 
imagine a field of production where stars would scarcely be necessary 
for a certain limited box office success. The trouble with such films 
is that their success is likely to be confined to the audiences whose 
associations and loyalties they affirm. I do not mean to deny the 
possibility of producing patriotic films which will lend themselves 
to general exploitation, but their patriotism, I fear, will have to be 
incidental to more universal sources of pride. It will have to be 
realized creatively in achievements all can appreciate rather than 
stated in the more exclusive terms of flag-waving and parade. 

Better Popular Pictures — Grierson 239 

Western civilization is so rich in dramatic material that there 
should be no great difficulty in accomplishing this. There are subjects 
aplenty in the progress of industry, the story of invention, the pioneer- 
ing and developing of new lands and the exploration of lost ones, the 
widening horizons of commerce, the complexities of manufacture, 
and the range of communications : indeed in all the steam and smoke, 
dazzle and speed, of the world at hand, and all the strangeness and 
sweep of affairs more distant. If this material were treated imagina- 
tively and energetically with all due regard to the nature of the 
medium and the nature of the institution, it would cut through to 
the very sources of Western pride and patriotism without over- 
stepping the laws of international decency. 

Part 2 

In the first section I have dealt with the nature of cinema as a 
popular institution and I have noted that a deepening of appeal is 
possible in certain directions without any interference whatsoever 
with the demands of the public. There is the complimentary problem 
to consider. What are the possibilities of cinema as a medium and 
which of these possibilities lend themselves best to popular pro- 

The interesting point in this connection is that not only does 
the popular demand allow for a worthy use of the medium, but within 
certain limits it ensures the development of cinema according to its 
own inherent nature, according to its own most obvious powers. 
These powers consist briefly in a preoccupation with movement 
which enforces a drama of action, and an insistence on the visible 
which discourages psychological niceties and all syllogisms whatso- 
ever; a flexibility which permits of inexhaustible variety in scene, 
setting, and dramatic emphases; a command over the natural which 
makes for authenticity (or "realness") and allows for the more ob- 
jective forms of poetry in which all can participate. Cinema is a 
thoroughly objective and in the main a non-intellectual medium; it 
is in its essence a popular one. 

These matters are more apparent on a consideration of the form 
of cinema development in Germany. The German product, except 
for one or two brilliant exceptions, has not begun to compete with 
the American in international popularity, and in the exceptional 
cases, production was partly imitative of the American model 
("Variety" and "The Waltz Dream"). The German school has come 

240 Transactions of S.M.P.E., August 1927 

to cinema from the stage and has been inspired from the first by the 
desire to appeal to the intelligentsia. Its form is an indoor form; 
its material is shot through with the psychological preoccupations 
which are more easily handled under stage conditions. The Germans 
seem to have been chiefly interested in the new medium because of 
its wider range of theatrical effects: it has given them a solution of 
their former troubles with the immobility of the stage. Their develop- 
ment of the medium has been so able in this single direction and their 
effects have been so fantastic and powerful, that German cinema has 
been regarded by many as truer to the nature of cinema than any 
other school and the one school to be imitated. This is a fallacy and 
a very dangerous one, for while it has helped the skill of other pro- 
ducers to absorb the technical ingenuity of the Germans, it has been 
responsible for any amount of dullness and any amount of artificial 
theatricality, which has nothing to do with the screen. 

The reason is that where cinema is preoccupied with affairs 
psychological (in other words with affairs essentially invisible and 
never adequately represented except in prose or in poetry) it has to 
load its visual effects of conduct and setting with undue emphases: 
and with its too meaningful looks and too deliberate movements, 
this medium of action is slowed up past average endurance. "Cah- 
gari," "New Year's Eve," "Back Stairs," "The Treasure" and a host 
of other German pictures provide ample illustration. The creaking 
of the dramatic machinery is of course much more obvious in the 
case of tragedy. 

Theatrical terms are peculiarly foreign to cinema. Theatrical 
effects are undoubtedly possible and possible to a degree unheard of 
under stage conditions owing to the camera's capacity for miracles 
of one sort and another; but expressionism which is accepted in a 
theater, where the light of day and natural effects are out of the 
question, becomes, if made the general rule, strained and unnatural 
in cinema, where the Hght of day and the wonders of the light of day 
are so clearly to be drawn upon. Not only do the majority prefer 
to have their drama easily and unstrainedly rather than in fantasies 
and grotesqueries which involve a detachment from the obvious 
sources of drama, but it is clear that in avoiding the natural world 
which it has at its comanand, cinema is depriving itself unnecessarily 
of much that lends itself specially to cinematic treatment. 

, Mr. Douglas Fairbanks, in a conversation with Mr. Robert 
Nichols, stated the other or non-German point of view very elo- 

Better Popular Pictures — Grierson 241 

quently: "Ours is a young, elastic and athletic medium," he said, 
"and youth, heroism and athletics suit it. We should keep it in the 
open air; cinema has gone indoors and consequently begun to wither." 

There are good reasons for this opinion, without the natural 
preference of cinema audiences, and without the natural preference 
of Mr. Fairbanks in favor of his own production. The lifesblood of an 
art of movement is obviously movement itseh, and while, by con- 
trolled tempi, arranged rhythms, powerful sets, and camera magic, 
great dramatic effects are possible in the theatrical tradition, the 
easier and richer and greater power of outdoor movement is missing. 
The thought of horses and waterfalls will serve to demonstrate this. 
The point is more ob\dous still if one takes account of the natural 
dramatic power of ships and the sea, of the flight of birds and the 
sweep of plains, of crowds in the streets and regiments on parade. 
The scale of movement is larger and greater variation is possible. 
And there goes with these the guarantee of more abundant visual 

There is another matter. The acting manner, however significant 
and dramatic it be made by theatrical emphases, is never in cinema 
nearly so effective nor ever so patently powerful as spontaneous 
beha\dor. "Children and animals are the best screen actors: they 
are themselves and the camera is relentless," Fairbanks added to his 
first comment. In Hollywood this capacity for naturalness is recog- 
nized in definite terms. Actors, they say, "have the bubble," or they 
lack it; they are "photogenetic," or they are not. The terms of course 
mark nothing but a sense of the distinction; but this has become so 
strong that directors and producers have to find satisfaction in the 
notion that the camera is some mysterious instrument endowed with 
"second sight" which reveals and exaggerates the distinction between 
the natural and the false. 

A partial explanation is that, faced by a world of silent forms and 
bringing people to a contemplation of them, cinema focuses the 
attention on the visual character of its figures in a way impossible 
in ordinary life and on the speaking stage. Where personahty has to 
register itseh within the hmits of shape, mass, and muscular move- 
ment, the race is ob\dously to those who are distinctive and pleasing 
in these matters and who in the ordinary course of events express 
themselves and have greatest character in physical terms. They very 
naturally include children, animals, athletes, men at their craft, 
primitives, and the like. 

242 Transactions of S.M.P.E., August 1927 

Naturalness or spontaneity is of course the best guarantee of 
the variation requisite for Hving interest. It is the guarantee that 
actors in the Garrick dictum shall act "with their legs also"; a dictum 
which from being of secondary importance on the stage becomes of 
first importance on the screen. It may be doubted if it has ever been 
possible for actors to pass into other characters to the extent of 
carrying the new character into the more subtle rhythms and manner- 
isms of their bodies; and indeed the stage focus on voice and words 
made it unnecessary. Where the point of focus is altered, and every 
movement tells in the sum of effects under the visual searchlight of 
cinematic conditions, the slightest falsity or the slightest deadness 
is apparent. 

In the first case as in the second, the uselessness of stage methods 
is apparent. The trouble with stage props and acted parts is that they 
tend to be visually shallow, and all the theatrical emphases in the 
world, be they as violent as the emphases of Meyerhold or of Lang 
only make it more apparent that the final source of visual personality 
and visual drama — the subtle uncontrollable nuances of movement 
to which in ordinary life one need not or does not pay attention — has 
not been drawn upon. The age-old native dance in "Moana" has a 
cinematic power which is unequalled by any staged efforts. The 
easy magnificence of "Nanook" handling his Eskimo spear, or the 
eagerness in the kill and the delight in eating which the hunger focus 
of his race has instilled in him, subtly defy the imitations of a mere 

Nothing in a word is so dramatically powerful for the camera 
as those characteristic gestures and rhythms of physical expression 
which long necessity has developed and time worn smooth. So far 
producers have understood this only superficially. They have 
"naturalized" studio production to some extent, but have not realized 
the rich sources of cinema material which lie outside, among the 
natural rhythms of e very-day life, among the natural rhythms which 
spell the character of cities, of occupations and peoples. This, 
however, leaves the more for other producers to do. In a sense, cinema 
has not begun to draw on its richest sources. 

These considerations are of. some importance for producers. 
They might prevent a repetition of certain errors of the past in the 
choice of personnel and dramatic material, and they might prevent 
any tendency to admire the continental model overmuch. But I do 
not insist on this point because, whatever its faults, American pro- 

Better Popular Pictures — Grierson 243 

duction has led the way to the natural, and no one shall say it has 
not been objective and non-intellectual. Despite the uncritical 
atmosphere in which it has developed, the American feeling for the 
open air and for action, and the hatred at the box office for things 
artificial and introspective and morbid, have combined to lead the 
American tradition of cinema aright. Pictures like "The Covered 
Wagon," "The Vanishing American," "The Iron Horse," "The Big 
Parade," "What Price Glory," etc., etc., and cinematic stars like 
Fairbanks, Pickford, Swanson, Vidor, Adoree, Dix, Coleman, Mc- 
Lagen, etc., indicate its essential rightness. Even the Russians, who 
might be expected to approach cinema with the same preoccupations 
as the Germans, have been very conscious of the superior naturalness 
of American cinema, and their latest efforts (if rather more intense) 
are in the American manner. They too have gone outdoors, and they 
too have realized cinema as a medium of action and spontaneity. 

The fault of American cinema, indeed, is not in the central 
principle which guides it but in its failure to supply the necessary 
refinements of that principle. 

While talking of the love theme and the adventure theme in the 
first section, I have hinted at one or two of the refinements which 
are possible in the naturalistic tradition. The American failure, such 
as it is, is largely related to a shallowness in visual imagination. 
I indicated how this appeared in the visual crudeness of love scenes, 
and in the triviality which so often accompanied efforts in epic. 

As a general rule, American pictures do not talk back into the 
environment enough; they do not play on it, fight it up, set it moving, 
intensify it enough, so that it really enters into the story and adds 
its visual character to the story. American production has had its 
mail robberies and its train robberies, its railroad smashes and its 
shipwrecks, its desert romances and its subway romances, its heroes 
of the steel mills and its heroes of the fire brigade, and it has had its 
adventures north, south, east and west all over the earth ball, 
wherever there was a pretty ankle and a scarlet giggle to give them 
a fade-out. It has covered much ground, and more than a wisp of 
modern life and energy has crept through. But excepting in some 
half a dozen pictures ("The Covered Wagon," "The Iron Horse," 
"The Vanishing American," "Moana," "Nanook," "What Price 
Glory," "The Big Parade," "Beau Geste," come to my mind) I doubt 
if the real cinematic essence of life and energy has been caught. 
There are stories — the Lord knows there are stories — and heroes and 

244 Transactions of S.M.P.E., August 1927 

heroines, and romantic clinches, and shootings and dyings, and 
sudden deaths, and frantic escapes. But I doubt if the guts of reahty 
is in many of them: of the reahty which would make the fade-out 
significant and the adventure really important. I look almost in 
vain for the cinematic reality of discovery and exploration and 
colonization, of the sweep of commerce and the dynamics of industrs^, 
of ships and docks, plains and plantations, factories and furnaces, 
streets and canals, dams and bridges, of trades, of professions, of 
cities, of peoples. The story (as often as not) sUthers through to 
the lolly-pop fade-out, without catching fire at the real source of 
visual energy and cinematic character. 

The world of cinema still awaits a proper handhng of epic ma- 
terial. The two countries which have tried to make pictures of the 
epic sort — America and Russia — seem to be prevented from going far 
by the nature of their approach. American producers are so bound up 
with what they call "human interest," and so insensitive to the 
dramatic importance of scene and setting, that in most cases they 
allow the more private preoccupations of their characters to destroy 
the sweep of events. They are slow to reahze that in epic cinema the 
event, whether it is a struggle of war or a struggle against the odds 
of nature, must properly dominate the personal aspects of the story 
and indeed be the tide on which the characters are carried. 

It ought to be obvious too that in epic cinema certain impersonal 
agencies may be very easily and very powerfully exploited. The 
visual character of a ship or a street or a city or a mountain pass can 
be built up till it becomes an effective motif in the picture, bringing 
it into the world of greater and more primitive energies and giving 
it size and intensity and power. But this too American producers have 
generally failed to recognise. In a recent picture which professed 
to recount the historic adventure of an American frigate in IMediter- 
ranean waters, neither did the ship hve nor did the adventure. The 
development of larger lives and greater events was lost in a petty 
sequence of fo'c'sle jests and sentimental amours. 

Or take the case of "The Vanishing American." "The Vanishing 
American" had a great story: there is no greater story than the 
passing of the Indian. And it had a great setting: it had the desert, 
the canyons and the plains to conjure with: it had the night rain-gods 
and the night luck-gods to conjure with. It began finely. The Valley 
of Vanishing Men took hold of the spectator and gripped him from 
the beginning. The primitive races came out from the rocks, they 

Better Popular Pictures — Grierson 245 

built their cave houses, they fought and were beaten. The Indians 
rejoiced in their -vdctor^^; the Spaniards came and the horses and the 
muskets; the advancing American of the new era came, and the 
soldiers, and the artillery. That was noble stuff. There was something 
of the wilderness of space and of the infinity of time written on it, 
that took one's breath away. The whisper of the winds of history 
was on it. But something failed at that moment. The last episode 
was the twentieth century stor^^ of how grafters took advantage of 
the Indian and stole his lands and how the twentieth century Red 
Man (Dix was amazing) loved the Httle schoolmistress. But how 
cheap and how trivial they made the story after that! The punch of 
the picture faded, the dignity of the theme vanished, the story lost 
the atmosphere of the vaUey and the sense of fate and became hke 
any other stor^^ of gentle, gentle heroines and nasty, nasty villains. 

The Russians, to take "Potemkin" as a guide, have gone to the 
other extreme. Communist interests have made them somewhat 
bhnd to personal themes and Trotsky's notion that the "apotheosis 
of the ordinary facts of personal routine becomes unbearable in an 
age where mass and speed are making a new world" finds its cine- 
matic expression in an emphasis on crowds, ships, streets and factories 
to the almost complete exclusion of individual life. 

It remains for any producer who cares to combine the good 
elements of the Russian and American schools, and avoid the faults 
of both. 'Totemkin" shows a marvelous capacity for orchestrating 
the visual details of a cruiser and a mob and making them both 
gigantic cinematic characters. In this the picture is unique, and 
technically ver^^ far in advance of any other production. If this 
advance were understood and the method used in conjunction with 
a greater feehng for story, the combination would be a powerful one. 

The secret of advance, as I have suggested, is that producers 
should appreciate more and more the value of the environment of the 
story. The environment must be more than a back-drop; it must be, 
itseK, dramatised cinematically and treated imaginatively, so that the 
story may draw sustenance and intensity from it. At its lowest level 
this may involve supplementing the ob\dous embrace of a meaning- 
less amour with a visual play on water, or trees, on meadows, on 
machiner^^, which expresses the mood and imaginatively articulates 
the situation. (In Vidor's "Bardelys" one of the most beautiful love 
scenes ever staged was effected cinematically by a plaj^ of willows 
and shadows and sunspots as the lovers drifted down the bank of a 

246 Transactions of S.M.P.E., August 1927 

stream. In Von Sternberg's "Exquisite Sinner" the romantic atmos- 
phere of a gypsy wagon and hfe in the woods was used charmingly 
to express all the feelings of the dramatis personae. There are other 
instances: but too few.) 

At its highest level, the dramatic use of environment would 
involve a cinematic exploitation of the intenser energies and deeper 
meanings of actual scenes and living people. It would involve a 
recourse to natural sources and a great deal more in the nature of 
expeditionary cinema than has as yet been attempted. Producers 
send their companies on location but it is a question whether in any 
real sense of the phrase, they send them far. Production seldom 
loses the atmosphere of the studio : indeed there are some who claim 
(Flaherty of "Nanook" and "Moana" is one of them) that it never 
does. No great attempt for instance is made in the case of pictures 
with foreign settings to add to the story the rich dramatic values of 
genuine native life. If the natives are used at all, it is as novelties 
in the background, as back-drops in a Hollywood illusion, adding 
a certain picturesque quality to the story, but seldom adding sub- 
stance to it. Nor is any great attempt made to add to a story the 
cinematic essence of actual scenes and actual activities. In one very 
notable instance — "Men of Steel" — an American producer did begin 
to do this: he exploited the resources of the United States Steel 
Corporation, and made his picture in Pittsburgh and on the docks 
on Lake Erie. Some of us waited, foolishly expecting great things. 
The exception as it turned out, only proved the rule. The cinematic 
possibilities of the steel mills and the ore ships were not reahsed 
at all: the cinematic possibiHties of workmen caught in the rhythm 
and roar of living industry were not guessed at. The director's 
camera was trained on the living center of modern masses and modern 
energy with the twentieth century and Western civiUzation at its 
feet, but his heart was back in Hollywood. He was in fact too busy 
telling his hokum story, to incorporate the enormous drama of the 
life about him, superior as it undoubtedly was from every cinematic 
point of view. He missed what might have been splendidly popular 
for what was only tawdrily titivating. 

It will be realised by this that the problem of future production 
is not so much a problem of setting as a problem of using it : using 
the settin_g cinematically, shooting the romance out of it rather than 
imposing the romance on it. Producers have varied their subject 
matter aplenty: but they have not changed the cinematic grip of 

Better Popular Pictures — Grierson 247 

the subject matter. The scene msiy be new but it is only included in 
the sense that it provides a fresh back-drop for the same old story. 
"Men of Steel" does not mean that the story of steel and the heroes 
of steel thunder their way across the screen: not a bit of it. "Men 
of Steel" merely means that another professional hero has melo- 
dramad his way to another professional heroine with Pittsburgh views 
in the distance. Cinema in other words has not reached out to the 
new material and taken it to itself. It has not been inspired to new 
combinations of visual effects, of tempo, of rhythm: it has not ripped 
its way into the dramatic intensity of labor. and life for the purposes 
of its story. And it has failed to do this though the greatest box 
office successes of cinema have been achieved in no other way. A 
cinematic handling of swinging trapezes meant a great deal to 
"Variety," a cinematic handling of the desert meant not a httle to 
"Beau Geste," a cinematic handling of wagons and plains meant 
much to "The Covered Wagon," and of wagons and marching 
troops to "The Big Parade," and "What Price Glory." It gave to 
each of them more elemental energy and a visual character more 
vivid to be attached to cinematic essences in this way. 

I may be able to suggest where the trouble begins. As I write 
this, there has come into my hands a scenario written by the most 
celebrated scenario writer of Holly w^ood. I read it over and I was, if 
anything, more fascinated by it than by any story in a twelvemonth. 
The ability shown in the mere telling was of a high order : the charac- 
ters were clear, there was action, clever situation, suspense, more 
suspense, and there was comedy relief. A lady (a pretty lady pre- 
sumably) hved as a king's mistress, her heart was with the people, 
she loved an artist, but in the end she hesitated between the pearls of 
great price and the things which are supposed to be greater than these ; 
and in the dilemma she lost. The story itself does not matter however: 
I merely wish to insist on the excellence of its execution as a story. 
The only thing indeed that was at aU lacking in it was cinema. I 
do not mean to suggest that the story was not told visually: it was, 
and scene followed scene with scarce a sub-title, developing the plot 
and bringing out the interplay of character. My point is that the 
story could have been told as well in novel form or in drama form : it 
had nothing in it that specially exploited the possibilities of the 
medium in mass, energy, movement, and in spontaneity. Scenes at 
court, scenes in the garden, scenes in the pavilion, scenes in the local 
tavern, deceptions, hidings behind curtains, conspiracies, escapes: 

248 Transactions of S.M.P.E., August 1927 

there they all were just as they might be on the pages of any romance. 
All the camera was commissioned to do was to follow the characters 
from place to place (with an appropriate sense of the intimate) and 
watch them doing this, that, and the other thing. The suspense of the 
events and the smart novelty of the situations were in complete 

A picture of this nature is of course limited from the beginning. 
It is of necessity an artificial or theatrical picture with its courts, 
and its costumes, and its unnatural roles, and the camera's love for 
authenticity has no great opportunity to show itself. But the point is 
not vital because there must always be a demand for unreal pleasan- 
tries of this sort, and cinema undoubtedly will go on reheving one of 
the labor of reading them. A more important consideration is that the 
scenario form when it has too much of a story focus, tends to starve 
the camera at its vitals. When the producer handed me the scenario, 
he described it strangely as ' 'fool-proof." All you have to do with a 
scenario like that, he said, is to look and shoot. Now I wonder. 
Is it really possible to write a picture in this way? Is it enough to 
have the situations and the sequences and the story arranged? Is 
it not precisely this very writing of pictures which has been responsible 
for half the cinematic deadness of pictures in the past? 

The point is that the scenario with a story focus is only the 
beginning of cinema. It may be very prettily hung together for 
camera treatment, and even full of human interest, yet avoid all 
those special cinematic effects which give punch and atmosphere and 
variety and loveliness to the screen version. A scenario proper ought 
to be a double barreled affair at the very least, with one column 
for the sequence of events, and a second (a much larger one) for the 
cinematic treatment, with appropriate details concerning tempo, 
imagery, composition and the like. But even then cinematic effects 
are so much the secret of the camera and so much the secret of the 
locale that it is doubtful if they can be prepared cold beforehand. 

I am merely suggesting a change of focus from the point at 
which people emphasize story sequences and think up environments 
for them, to the point at which people emphasize the cinematic 
power that may be taken from environment and think up a story 
to give human significance to it. I feel that the cart has been put 
before the horse in cinema, and that the true source of cinema 
drama (the world of movement and spontaneous behaviour) is not 
being drawn upon as much as it should be. There is a real difference 

Better Popular Pictures — Grierson 249 

of attitude involved. Lately I found myself arguing with an English 
cinema producer. He told me of a plan he had for a picture. Wife — 
husband — other party .... as in "Variety" .... he went on. I 
asked: Where is the source of visual energy and visual gaiety? .... 
where the trapezes? .... and the side shows? He had not thought 
of them! 

It is clear of course that the argument leads finally to an analysis 
of how imaginative visual effects are to be got, — of how effects of 
tempo, composition, imagery, and the like, can be built up to the 
greater visual glory of a picture. Any extended discussion of better 
pictures would have to undertake this analysis and show specifically 
in what directions visual imagination can be given greater play. I 
shall leave these matters however for another occasion. I am content 
for present purposes to suggest that — within the limitations of 
popular demand— the greater play of visual imagination is possible, 
and even desirable. 

Another Hyper-sensitizing Process. — Two Berlinese (Germany) 
investigators, Moise Safra and Reimar Kuntze, have it is announced, 
made a wonderful discovery by means of which an interior set may 
be taken by the hght of a single incandescent lamp. For outdoor 
work it enables one to take dark woodland scenes, late evening and 
night effects. This wonderful result is attained by passing the film 
through a certain chemical bath. The only disadvantage is that the 
film must be used within a month; "but it is hoped to overcome this 
defect as preliminary experiments have proved this to be possible." 
According to the inventors excellent results have been secured of a 
group illuminated by red light only. (Le Cineopse, 1927, 9, 340). 

Silver-free Oza Film. — This is a positive film prepared with 
cellophane, a derivative of viscose. A positive is obtained from a 
positive and so far only red and dirty violet images result. A mercury 
vapor lamp must be used for exposure and development is effected 
with ammonia vapors. It is stated that the images can be toned and 
dyed and its price is one-third of the ordinary celluloid films. (Film- 
technik, 1927, 3, 149). The description would lead one to assume 
that the Kogel-Kalle patents— U.S. P. 1,444,469; D.R.P. 302,786; 
371,385; 386,433; 383,510; 386,434, are used. 


By Herford Tynes Cowling* 

THIS paper describes the use and care of motion picture negative 
film which is to be exposed in tropical countries and far away 
from the home laboratory. 

The immediate action of light on sensitive film is the production 
of a latent image and an invisible picture which can only be made 
apparent by the process of development. With modern materials 
the camera man knows that a certain exposure in a certain hght 
with the appropriate lens aperture will produce a definitely pre- 
dictable amount of latent image which when developed, either today 
or tomorrow or next week will yield a picture of equally predictable 
intensity. He can rely on the latent image enduring unchanged 
until he wishes to secure its development. 

It is a little realized fact, perhaps, that under abnormal con- 
ditions of heat and moisture, especially in those hot countries where 
bacteria and fungoid moulds abound, the latent image is not quite 
so permanent as we are wont to believe. Little by little as each week 
passes in the traveler's journey towards home, the latent image may 
become weaker until by the time the film reaches the laboratory only 
a very feeble picture can be revealed by development. 

My own personal experiences in tropical countries, especially 
during the humid rainy seasons, has shown that there is generally 
a pronounced fading of the latent image together with much general 
fog on development unless certain definite rules are followed. I 
have found it advisable to treat the problem from two angles. 
Firstly, it is wise to increase the camera exposure so that there is 
more latent image to withstand fading; secondly, a scheme of packing 
must be employed which ensures protection against these harmful 
atmospheric conditions. By adhering to a few common sense rules 
I have found it quite feasible to keep negative film from a minimum 
of four months to a maximum of nine or more (depending on con- 
ditions) between the exposure and the development. One lot of 3000 
ft. exposed in Sumatra, under the grueling heat of the equator, did 
not arrive home till ten months later, but owing to judgment in ex- 
posure and care in packing there was very little which was not of 
excellent quality. 

* Eastman Kodak Co., Rochester, N. Y. 

250 • 

Film Care in the Tropics — Cowling 251 

We may divide the life of negative film into four periods; that 
which elapses: 

(1) Before opening the sealed unit which comes from the 

(2) Between opening the unit and placing the film in the camera ; 

(3) While the film is in the camera; 

(4) Between exposure and development. 

1. Care in Shipping and Before Opening the Original Container. 

Negative film is comparatively safe from decay whilst resting 
in the original metal container in which it comes from the manu- 
facturer. When once this has been opened, even though it be im- 
mediately resealed with tape, moisture and bacteria have been ad- 
mitted and the films future history becomes a matter of doubt. 
Experienced travelers and explorers adopt a unit system of packing 
and avoid opening any of the film as originally packed until required 
for use. Among the items to be specified when the negative film is 
ordered from the manufacturer the following are important: 

1 — Type of camera in use; 

2 — Length of rolls required; 

3 — Method of winding peculiar to the particular camera in use ; 

4 — Kind of negative desired; (Par-Speed, Super-Speed, or 
Panchromatic) ; 

5 — Size of unit packing desired; 

6 — Number of rolls of adhesive tape and black paper required. 

The unit system of packing employs a series of three containers, 
each larger unit containing a number of smaller units as follows: 

First Unit: This should hold the length taken by the camera, 
whether 50-100-200 or 400 ft. rolls, sealed, double-taped, original 
metal containers as supplied by the manufacturer. 

Second Unit: This should comprise 5 first unit rolls placed in a 
larger metal container and hermetically sealed with a very thin 
sheet of soft metal to allow for opening with a pocket knife. An ad- 
ditional double-taped cover should be provided so that the second 
unit can be used for repacking the first units after exposure. 

Third Unit: This consists of a metal-lined, wooden shipping 
case containing 4 to 6 Second Units. The sealed metal lining can be 
taken out of the wooden shipping case and put into fiber cases or 
other carriers for local transport without opening the metal. Maxi- 
mum weight, not including wooden shipping case is forty pounds. 

252 Transactions of S.M.P.E., August 1927 

A supply of one inch width adhesive tape in rolls sufficient to 
double tape all the first and second units after use, also new black 
photographic wrapping paper in a sealed roll sufficient to rewrap 
the film, should be included in this unit. 

The larger unit may also be used to pack other photographic 
supphes used on the trip, including plates, film rolls, etc., and which 
may also be wanted on the unit system. Photographic supplies should 
be kept separate from any unit containing other supplies. 

Shipments to agents or representatives in foreign countries 
should be accompanied by strict instructions to store in a cool dry 
place : In this connection it is advisable to call attention to the fact 
that the medium of transportation known as Express in the United 
States is peculiar to the United States and Canada alone and does 
not exist in other countries. Consequently goods shipped by Express 
from the United States becomes freight at the port of embarkation 
and moves as freight upon arrival in and during railway transit 
through any foreign country and freight moves extremely slowly: 
The term ''Goods" is used instead of freight abroad. This is very 
important when shipping perishable goods. 

The best way to supply film for any expedition, is to have it 
shipped to the nearest shipping point by the manufacturer well in 
advance of need. Otherwise take it as baggage, though there are some 
complications and important things to know about the latter. 

All film is subject to custom duty charges in every country and 
custom officers are not everywhere familiar with the sensitive nature 
of film, resulting in their often opening a few cans to determine the 
nature of the goods. Also nearly all steamship regulations require that 
all films go as deck cargo and prohibit their presence in the baggage 
room or cabins. The best place for cases of film on a steamer, if 
prohibited in the cabin, is in some sheltered position on the deck where 
it can be kept cool and dry. It is inadvisable to store fihn near the 
engine room where it will be subject to heat and violent vibrations, 
nor should it be put in the ship's refrigerator, as this is entirely un- 
necessary. It is not necessary to use any hygroscopic chemical for 
the assumed purpose of maintaining a dry atmosphere with the 
containers; indeed this is a dangerous and messy procedure. 

If negative film is specially packed by the manufacturer for ex- 
port and care exercised in transporting, no fear need be maintained 
for its safe keeping qualities. 

Fibn Care in the Tropics — Cowling 253 

Par-Speed negative film specially packed for me by the Eastman 
Kodak Company, as described, has kept in perfect condition for over 
two years and withstood varying changes of temperature and 
conditions of travel through Central Africa, India and around the 
world on my various expeditions, without any loss. 

Another item to be noted ■ in taking motion picture film as 
baggage is that all ports of England prohibit any motion picture film 
being brought into England as baggage, and regulations there impose 
a large fine for offenders. This does not refer to the question of custom 
duties, but is an arbitrars^ rule against entering England with moving 
picture film as any type of baggage, either hand baggage or in trunks. 
The only way to avoid trouble at an English port is to list the film 
cases on your steamer as ships cargo and have it placed on the ship's 
manifest. The fact that film is ''left in bond" in a port does not affect 
this rule. This rule does not exist in any other country but applies 
to all ports of the British Isles. 

All film, whether manufactured in the United States or not, is 
subject to a custom duty charge upon return to the United States 
if it has been exposed abroad. 

Care should be exercised to avoid taking film through several 
foreign countries in baggage, as custom duties are demanded in 
each country. Few countries have arrangements for baggage to be 
checked through transit "in bond" and demand that custom duties 
be paid on a "refund basis." Such procedure takes months of delay 
and is decidedl}^ impractical. Fihns should therefore be shipped direct 
to the nearest shipping point to destination whenever possible. 

Under conditions customarily encountered in local transportation 
where goods are transported upon backs of coolies, pack animals, 
etc., they are subjected to considerable jolting as well as changes of 
temperature and weather. 

During the rough travel the third or larger units should be pro- 
tected by wrapping, with both a straw-matting and a cheap water- 
proof cloth tied with rope. In the absence of straw-matting it is well 
to use the cheap red cotton blankets, obtainable in the native bazaars, 
as an inside wrapping. These coverings serve as protection against 
vibration, moisture and extreme heat. 

In extremely hot climates, like Central Africa, and on long mar- 
ches in the sun, the waterproof should be wrapped inside and the 
package kept cool by occasionally wetting the outside straw-matting 
cover. The rapid evaporation keeps the temperature down. Care 

254 Transactions of S.M.P.E., August 1927 

should be exercised to see that porters do not leave their loads 
containing these units directly in the sunshine unnecessarily for long 
periods during the heat of the day. 

2. After Opening — Before Exposure 

Negative film should not be rewound before using in the camera 
if it can possibly be avoided, as the emulsion thereby absorbs moisture 
from the atmosphere during the rewinding. This also allows foreign 
matter, such as very fine dust to settle and adhere to the surface as 
a consequence of the electrification of the film during rewinding and 
this will ultimately cause minute spots on the picture after exposure. 
Also "static markings" are likely to result from friction that is de- 
veloped in the rewinding operation. 

It is well to open only one of the third or larger unit containers 
at a time, carefully protecting the contents from moisture. The 
best time to open these units is at night when it is often cooler than 
during the day. Heat has considerable effect on the fihn emulsion in 
the presence of moisture, so that changing in a moist atmosphere 
should be avoided whenever possible. 

As soon as the film has been taken from the inner first unit or 
original container, as it was sealed by the manufacturer, it begins 
to spoil at a rapid pace and continues to do so until it is exposed and 
developed. Thus care should be exercised not to load film into the 
camera magazine any earlier in advance of use than possible. A 
good spacious Hght-tight changing bag such as the 'Tngento" is 
most essential for this purpose and will allow for quick loading of the 
film rolls into magazines just prior to use as well as temporary re- 
packing very soon thereafter. 

The greatest dangers to be avoided after loading in the magazine 
are the absorption of moisture from the air and friction from transport 
vibration. The film is naturally free in the camera magazine and al- 
though wound tightly in a roll to exclude all possible air from entering 
when packed, as soon as the tension of the wrapping is removed it 
will "loosen up" in the roll. This "loosening up" allows access of 
atmospheric moisture and heat to the emulsion surface and at the 
same time the coiled layers of film shde from side to side upon each 
other, thereby developing minute friction markings. This is, of 
course, true both before and after exposure. 

Film_ loaded in magazines and transported for some time in motor 
cars over rough roads and on trains invariable loosens up and develops 
minute friction or "rain streaks" from vibration. 

Film Care in the Tropics — Cowling 255 

This trouble can be considerably lessened by wadding the black 
paper, in which the film is originally wrapped, inside the camera 
magazine so as to wedge the film roll tightly and thus prevent 
"loosening-up," but, of course, the black paper must be removed from 
the magazine by the use of a light-tight hand-changing bag before 
use in the camera. 

It is also advisable to use waxed paper to wrap camera magazines 
loaded with film, when they are not sure to be used the same day 
as loaded, to prevent moist air from passing into the magazine both 
before and after exposure. 

When working near salt water additional precautions against 
exposure to the atmosphere should be taken owing to a more rapid 
deterioration of the film emulsion from contact with the chemicals 
which are carried in suspension in the air. 

3. Exposure in the Camera 

Correct exposure in the camera depends, in a large measure, on 
the approximate time interval that must lapse before development. 
If the film is to be developed in the field or shortly after exposure, say 
one to two weeks, normal exposure is sufficient and there is no definite 
rule for an increased exposure ratio in anticipation of delayed develop- 

Exposure meters are invaluable as a basis for ascertaining the 
correct exposure for immediate development, but no allowance is 
made for the lapse of time during a delayed development interval. 

4. After Exposure and Before Development 
After negative film has been exposed in the camera, it should be 
repacked with black paper and taped in the original first unit con- 
tainer, as soon as possible without rewinding. Often it is not prac- 
ticable to do this packing with the necessary thoroughness during 
field operations. The films must then be placed temporarily in 
the tins until a dark room is available and a number of exposed rolls 
have accumulated, and until drier condition of the atmosphere pre- 

The thorough final packing of negative film after exposure re- 
ferred to above, for delayed development and transport, should be 
conducted in a dark room if possible, although it can be done in 
a light-proof changing bag. The old black wrapping paper, wooden 
spool or core, and tape, which came in the original package, should 
be entirely discarded and fresh black photographic wrapping paper 

256 Transactions of S.M.P.E., August 1927 

and fresh adhesive tape used. Never use newspaper or any kind of 
wrapping paper other than black photographic wrapping paper to 
repack fihn, as most paper contains chemicals injurious to the sensi- 
tive film. 

The original containers should be v/ell dried out with the flame of 
a candle to remove all moisture. The film roll must be drawn as 
tightly as possible without "pulHng" and wrapped tightly with the 
new black paper. After placing the film inside the dried container, the 
center opening and every possible space available, is filled tightly with 
dry, fresh, black paper. When the cover is placed on the container 
under pressure, it should exclude all possible air from the container, 
and a double wrapping of new tape should be tightly drawn around 
the cover edges to seal the container. The tape should then be sealed 
over with a coating of hot paraffin wax, for which purpose melted 
candle wax will serve yqij effectively. 

The original container should then be repacked in the inside 
second unit containers, in the same manner, after which the film is 
ready for shipment to the laboratory for development. 

All of the same precautions as mentioned under "care before 
exposure" should be even more carefullj^ observed after exposure, 
as the film is now more susceptible to injur^^ than before exposure. 

Field Develoyment'^''^ 

It is more practical to utilize the delaj^ed development method 
of operation than to attempt field development of motion picture 
negative film except at considerable expense, and by expert handHng. 
Developing motion picture negative film b}^ the use of portable equip- 
ment in the field requires considerable care and skill. But, whenever 
possible, it is advisable to develop short-test strips to determine 
the correct exposure ; which exposure can then be increased for delayed 

^ "The Handling of Motion Picture Film at High Temperatures," by J. I. 
Crabtree, Trans. Soc. M. P. Eng. No. 19, 39. 

2 "The Development of M. P. Film by the Reel and Tank System," by 
J. I. Crabtree, Trans. Soc. M. P. Eng. No. 16, 163. 


J. B. Engl* 

AT THE present time quite a number of different methods are 
^ known how to record and reproduce sound waves for the purpose 
of the so-called talking film. With most of these methods the sound 
variations are photographed on a moving film-strip. Corresponding 
pictures and sounds being recorded on one common carrier, the 
synchronized reproduction of both picture and sound records can 
never be questioned. 

These methods of recording (I only mention here the names 
of different systems: Tri-Ergon, DeForest, Case, etc.) are a great 
advantage compared with the old method of recording the sound 
waves on a phonograph-disk and synchronizing the rotating phono- 
graph-disk with a mo^dng film-strip by means of special, more or 
less comphcated machines. 

These photographic recording processes have all in common a 
combination of a microphone, an amphfier, and a light source con- 
trolled by the amplified microphone currents. It is assumed and is 
to be proven that the intensity of the light source is varying with a 
linear function of the intensity. of the sound-source. 

The hght variations are photographed on the film-strip and 
appear after developing as density-variations, more or less trans- 
parent parts arranged in a so-called step-ladder-pattern. Positive 
prints from the negative are made, and used in the reproducing 
machine to generate photo-electric currents in photo-electric cells 
which are expected to be strictly proportional to the original light 
variations of the glow-Kght.** 

Now it is known, that densities produced by exposing a light- 
sensitive emulsion to light and developing it have not a simple relation 
to the original Hght intensities used in the exposure. 

In Fig. 1 a graph is shown where different intensities of light 
acting upon a Ught-sensitive emulsion are plotted against the values 
of produced density. There is only one portion which is practically 
a straight line, and which corresponds with a range of normal ex- 
posure. Below and above this straight line portion the curve is bent. 

* Technische Hochschule, Berlin. 
** A light source of the Geissler tube type. 



Transactions of S.M.P.E., August 1927 

Abscissas are plotted to the logarithms of the illuminating intensity, 
ordinates are the so-called densities S. The values for S are defined 
by the following formula : 

S = logiQ-j = log 10 U {1) 

U=^ = 10S. 

U is called the opacity of the developed film as measured by any 

photometric arrangement. 

Jo is the intensity of the light-ray, which is used in the photo- 
metric work and which impinges on the film-strip, J is the intensity 
of the light-ray after passing through the film-strip. A similar 
formula is valid for the positive emulsions. The curve of Fig. 1 can 
b6 divided in three parts. The beginning being curved corresponds to 
small illuminating intensities, the middle portion, which is almost 

Sound Records — Engl 259 

a straight line, gives the range of normal exposure, and the upper 
part of the curve corresponds to an over-exposure. 

In the reproduction of a photographed sound-record, a light-ray 
is passed through the positive print which is run through the machine. 
By special optical systems a brilhant hght-hne is focused on the film. 
After passing the film, the intensity of the Hght-ray is more or less 
diminished on account of the opacity of the print, which varies at 
different points of the print. As the film-strip is moving with a 
constant speed, the intensity of the light-ray is varying around an 
average. The light-rays falling on a light-sensitive electrode of a 
photo-electric cell create there alternating electric currents. For 
reproduction purposes it is preferable to have as large photo-electric 
currents as possible, the photo-electric currents being normally only 
a few microamperes. Any increase in current intensity is valuable. 
The amount of Hght passed through the film varies around an average, 
going from zero, meaning absolute opacity, to a maximum of absolute 
transparency. The average, therefore, should be just 50% of the 
Hght-intensity which is passing through the most transparent points 
of the record. Absorptive powers of about 50% are located in Fig. 1 
in the beginning of the curve. Hence it is clear that there cannot be 
any proportionahty between photo-electric current and intensity 
on account of the curvature. Doubtless, the characteristic curves 
of the recorded sound waves must be distorted in the reproduction. 
It is not possible, therefore, without special methods to get an ideal 
quality of sound reproduction. 

In the negative record we have not necessarily to use as small 
densities as in the positive print. For the printing process itself the 
density of the negative is not of great importance as we can easily 
increase either the printing light or decrease the printing velocity. 
But assuming that we are utilizing in the negative record the straight 
line portion of the curve, we can not get rid of the distortion caused 
by the above explained properties of the positive emulsion. In the 
following I give a method of developing which overcomes this diffi- 
culty. The idea is to develop the negatives in such a way that an 
artificial distortion is created which compensates the distortion 
made in the positive print. It is possible to develop so that the 
deviations from a straight-line-characteristic in the positive print are 
just compensated by analogous deviations in the negative record. 

Before I show how these final results were obtained, I will 
explain how the results by the different developing processes were 


Transactions of S.M.P.E., August 1927 

tested. In Fig. 2 results with different developing baths and with 
emulsions of different properties are graphically represented. Looking 
at the curves in Fig. 2 we see that an appreciable distortion exists, 
caused by the above mentioned properties of the photographic 
emulsion. As abscissa currents flowing through the glow light are 
plotted, as ordinate currents flowing through the photo-electric cell. 

The densities were measured in the following way. One film-strip 
was run with constant speed through the recording camera. The 
moving film was illuminated by the glow-light. The intensity of 
the glow-light was varied during the running of the film with the 
intention to expose the film to several known illuminating intensities. 
The currents which corresponded to those glow-light intensities 
were measured before and after exposure with all precautions con- 
cerning the constancy of the glow light current. 

Sound Records — Engl 261 

In order to get the different glow-light-discharge currents the 
glow-Hght tube was connected in series with the plate circuit of the 
ampHfying tube. By changing the grid potential of the amphfying 
tube by means of a potentiometer device between cathode and grid 
it was possible to get a series of known glow hght currents. Of course, 
the voltage of the plate battery had to be exactly the same during 
the recording of the density marks which were to be compared later on. 

These density marks were printed on strips of positive emulsion. 
They were developed for a definite time, in a developing bath of 
definite composition, and of definite temperature. After fixing and 
drying, the densities of the corresponding marks on the positive strip 
were measured with a photometric arrangement. This consisted of a 
photo-electric cell, an optical system with which a small part of 
the density mark was illuminated and a light source of constant 
light intensity. A diaphragm of small aperture allowed only a small 
part of the density mark to be illuminated. The illuminating light- 
source was a tungsten lamp with a small strip-shaped filament. The 
voltage in the tungsten lamp circuit was smaller than the normally 
allowed voltage in order to be sure of a constancy of light-emission 
for a long time. Constancy of light-emission was controlled by 
measuring the energy consumption, holding the current with an 
ammeter and the voltage between the lamp terminals constant. 
The tungsten lamp was lighted always a sufficient time before it was 
really used for measurement. 

The photo-electric currents were measured with a high sensitive 
galvanometer in the cells' circuit together with a constant battery 
voltage of 50 volts. As the constancy of the light-sensitivity of a 
photo-electric cell, measured by the currents, depends on the voltage 
between the terminals of the cell, the constancy of the battery had to 
be controlled during all measurements. 

The curves of Fig. 2 show that there is no proportionality 
whatsoever between the glow-light current and the photo-electric 
current. The curves represent only a small number of the measure- 
ments of several series of density-marks made under about 30 different 
conditions. The dotted straight line in Fig. 2 shows which relation 
between glow-light current and photo-electric current is desired. 
The shape of the curves represents, more or less, the beginning of 
the known "/S" shaped curve which is given in Fig. 1. The dotted 
line in Fig. 2 shows that a glow-hght current of 15 MA should 
correspond to a photo-electric current of 50% of the maximum 


Transactions of S.M.P.E., August 1927 

photo-electric current. The current of 15 MA in the glow-hght tube 
was the average current which was modulated above and below its 
value. The smallest glow-Hght current should produce a value of 
J/Jq = 0, maximum the value of J/Jo = l. It may be mentioned 
that all the values J /Jo are reduced by the value of the fog density 
as well as by the absorptive power of the celluloid base. The value 
Jo corresponds, therefore, to the light intensity after passing through 
the celluloid base and the fog density. 

The curves of Fig. 2 show that the transparency of the positive 
marks does not increase with increasing glow-light current in the 
same ratio. Transparency of positive marks means opacity of negative 
density-marks. The problem was to have the opacity of the negative 
density-marks increasing with increasing glow-light current at least 
in the same ratio as at small glow-light currents or with a greater 
ratio if possible. This was shown possible by using an abnormally 
long developing-time of the negative density-marks. 

Sound Records — Engl 263 

Fig. 3 gives some curves which show the effect of increasing 
the developing-time on the density of the negative density-marks. 
Abscissa is again the glow-hght current, ordinate is the value Jo/ J 
of the corresponding density-marks. Three curves are shown corres- 
ponding to the developing-time of 15, 20 and 30 minutes in a normal 
hydroquinone developer. It is apparent that the steepness of the 
curves increases with increasing developing time and what is most 
important that by this over-developing process the steepness for 

large glow-light currents is remarkably greater than for small ones. 
Of course, a very dense general fog is produced by the over-develop- 
ing. It was possible to reduce the veil by using a sufficient quantity 
of potassium bromide in the bath. 

If the negative film was developed in this developing bath for 
25 minutes, and if the positive print was developed 4 1/2 minutes 
in a normal developing bath for positive emulsions, I found a series 

264 Transactions of S.M.P.E., August 1927 

of density-marks on the positive print which is shown in Fig. 4. 
You can see that the curve is as straight as possible. A glow-Ught 
current of 15 MA corresponds with a transmission of 0.5. This is 
correct, of course, only for a definite value of the printing light. 

What is shown above as a result of a series of experiments, can 
be deducted theoretically as conditions, which must be satisfied 
by contrast-coefficients of the negative and positive emulsions. 
Following the law of Bunsen-Roscoe and Schwarzschild, we can 
write the relation between the density produced on a light sensitive 
silver-bromide emulsion and the light intensity : 

(2) S = v*log {a Up) 

S — the density defined as above by (1), a is a number factor, i is 
intensity of illuminating light, t is the time of exposure, and p the 
parameter of Schwarzschild. 

The factor p is constant in the straight line portion of the curve 
of Fig. 1, it is variable in the bent parts of the curve. The amount 
of light which impinges on the negative film during the exposure 
we can write as: 

(3) In = a'iitP- 

where ir is the glow-fight current during the exposure and a is a 
proportionality factor. 

For the density of the negative, Sn, we get, using formula (2) : 

(4) Sn = v' log {aJn) = log (a^ a ij 1^'') " 

In the printing process a printing light intensity /q may be used; 
it is weakened by passing through points with a density Sn- 

The light intensity Ip acting photochemically on the positive 
emulsion is therefore : 

(5) Ip = Io 10-^^ = /o {anaiiiP^)-' = Io {anatP^)-H-' 
As density Sp in the positive print we get the value: 

(6) Sp = Tr log (bplptpp) 

Here tt is the factor for the positive emulsion which corresponds 
to the factor p in the negative emulsion, 6 is a proportionality factor 
and Pp is Schwarzschild's factor for a positive emulsion. 

Using (5) we get for the density Sp : 

(7) Sp = \og(bptPpy Ip^ = log[{bptPpy I,^ {anaf)-'- ir'^] 
The opacity Up of the positive film is : 

{bptppy L"" / ty / ty 

(8) - up= 10 Sp=^^^^-^+ir' {-) - -) 

(ana ' tP"") \li/ \li/ 

Measuring the opacity Up with a photo-electric cell we have : 

Sound Records — Engl 265 

(9) u,= j 

where J represents the photo-electric current generated by the hght 
after passing through the positive film. Jo represents the photo- 
electric current created by the light intensity when there is no 
absorption by the density-marks. Comparing (8) and (9) we see 
that J is proportional to the glow hght current ii: 

1 J 

(10) - = - ^ (^,)- 

up J, 

if the product 7rp=l for all points of the characteristic curves of 
positive and negative emulsions which are used. 

By the just described method of over-developing the parameter 
V was increased on all points of the curves where the parameter w 
had too small values. 


Mr. Hill: I should like to ask what the resolving power is, 
that is, how many lines to the foot? Do you not have to stop with 
loud speakers letting through 16,000? If you have any sound repro- 
ducing apparatus in Germany responding to 16,000 you are quite 
a few cycles higher than we are over here. If you have loud speakers 
letting through 16,000, you have us stopped; we have to shut off at 

Dr. Engl: With this process, the upper limit of resolving power 
is the size of the grains of the emulsion and these vary. One is 
obliged to use a very sensitive emulsion to obtain enough density 
on the negative and have then larger grains than in the positive with 
which I succeeded in recording frequencies of 16,000 per second, which 
is more than sufficient for sound recording. The upper limit of hearing 
differs with different human beings. As you know, with increasing 
age this upper limit goes down, but at your age you can easily hear a 
frequency of 16,000. Frequencies of 1,000 are reproduced with much 
better efficiency than those of 15,000, but, of course, something will 
be heard; especially if electrostatic loudspeakers are used. 

Mr. Tuttle : At what speed is the film run to obtain a frequency 
of 15,000? 

Dr. Engl: In these experiments it was about 2 feet per second. 
The light-line projected on the film was very small — smaller than that 
generally used for recording sound photographically. 

266 Transactions of S.M.P.E., August 1927 

Mr. Mayer: I do not think that many of us are famiUar with 
the glow lamp. 

Dr. Engl: Glow-light-discharge apparatus consists of a glass 
filled with gas, with two electrodes sealed in its wall. That used in our 
experiments has as cathode a metallic rod, and as anode a second thin 
wire electrode. If there is a difference of potential between the elec- 
trodes, the gas between them is ionized and one sees — in the case I 
speak of the vessel was filled with argon — a bluish light around the 
cathode. In an incandescent lamp bulb we have a different physical 
fact. Here there are two seals but between them is a metallic connec- 
tion and the glowing part has a high temperature and emits a cor- 
responding radiation. In the other case there is no high temperature, 
but yet radiation. The glow-light-discharge is characterized by the 
fact that the radiation produced is independent of the temperature 
of the process. In the carbon arc, there is a high temperature on the 
cathode. The glow-light-discharge gives a different kind of radiation, 
which we call a fluorescent radiation. The light of the glowing cathode 
of the carbon arc is a temperature radiation, depending only on the 
temperature. The radiation emitted by the glow-light depends not 
on the temperature, but only on the electric current, which flows 
through the discharge tube. I believe this is a definite difference be- 
tween the two kinds of radiation. 

Mr. Jenkins : Did I understand that you use argon, and do you 
find that the light follows pretty accurately the current in the 
potential, the modulation of the current? 

Dr. Engl: Argon was used because it gives a strong actinic 
radiation. The potential depends on the gas pressure. In order to 
obtain high brilliancy on the cathode one should use pressures of 
several millimeters of mercury and a potential difference about 
500 volts. I have recorded frequencies of more than 10,000 per second. 
With this type of gas discharge about 200,000 or 300,000 per second 
have been recorded by others. The modulation of the current is 
good. A high frequency discharge of a condenser was passed through 
the tube. If you use two co-axial wire electrodes in a cyHndrical tube, 
a cylindrical glow-light layer is obtained round the wire and this 
fight changes in length when the current is changed. Length varia- 
tions were recorded on a moving photographic plate. Lines of 
varying lengths are obtained and one can compute the damping 
coefficient of a circuit by measuring the decrease of the amplitude 
of the oscillation. It is equivalent to modulating the high frequency. 


George A. Mitchell* 

THE use of miniatures in motion picture productions, where a 
part of the scene is normal action, and part built to a smaller 
scale, especially where there is action in both exposures, has called 
for a positive acting high speed movement. 

In the taking of these scenes it has been customary to employ 
two cameras, one for the high speed or miniature, and another for the 
normal takes. 

In the photography of animals especially, and other scenes, it is 
desirable to have a camera which operates as quietly as possible. 

The folloT\ing is a brief description of a movement designed to 
meet these requirements. 

Fig. 1 

Fig. 1 shows the movement unit, the gear box, the dri\4ng shaft 
and large crank. The movement is interchangeable in any of our 
cameras, no machine work being necessary-. On the gear box are three 
places to attach the crank, and two places to attach the driving shaft. 
On the top of the box is a gear shift lever, and with this arrangement, 
eleven speed changes are possible, from 2-128 pictures per second, 
the operator turning the crank 120 per minute, or normal. 

The extension shaft centre has a "Y" groove on each side and 
corresponding grooves in the outer casing. These grooves form a ball 
race, and instead of keys we use balls to drive. By this method no end 
thrust can be transmitted to the camera. 

* Mitchell Camera Corporation, Hollywood, California. 



Transactions of S.M.P.E., August 1927 

Fig. 2 

Fig. 3 

New Camera Pull-Down Mechanism — Mitchell 269 

Fig. 2 is a larger view of the movement mechanism, showing the 
pilot pins in the film, and the pull-down claws disengaged and return- 
ing to the top position. Two claws are used on each side for pulling 
the film, and the claws and pilot pins overlap, one entering before the 
other disengages. 

The pull-down member slides in part A, and pivots at the same 
point. Two cams of the same design but of different throw operate 
the pull-down and pilot pins. The pull-down is a curved path approxi- 
mating the natural curve of the film. To thread, screw B is loosened, 
and bracket C carrying the driving gear cara and pull-down arm, is 
moved to the rear as shown in Fig. 3, while the pilot pins are disen- 
gaged, enabling the operator to slide the film in slot D. 

This slot will accomodate two thicknesses of film for special 
work, and matting 1/16 of an inch in front of the film may be done at 
opening E. By loosening two clamps, FF, the front plate may be easily 
withdrawn for cleaning. The pressure plate is made with two rollers 
in the center of the aperture, and two steel shoes over the perforations, 
so that no pressure is on the picture area. This has a constant pres- 
sure of a very light spring. The rollers are made of ebony, with a steel 
core. The film race is of stainless steel. 


Mr. Ceabtree: In the mechanism described the gate is flat, 
but I think that with only a slight modification the same mechanism 
could be used in a printer fitted with a curved gate. 


J. I. Ckabtree and C. E. Ives* 

IT IS very necessary to remove all excess moisture from motion 
picture film after washing and before drying in order to prevent 
the possible formation of markings during drying.^ This is especially 
true if the gelatin coating of the film is abnormally swollen, which 
condition may exist in warm weather if the processing solutions are 
not kept at normal temperatures or if the film is insufficiently hard- 
ened either before or during fixation. 

When developing motion picture film by the rack system it is 
customary to wipe the film with absorbent cotton, chamois, or sponge 
during transference to the drying reel,^ but this involves the expen- 
diture of a considerable amoufit of labor and the gelatin coating of the 
film is liable to be scratched unless great care is exercised in the 
wiping process. 

The most satisfactory method of removing excess moisture from 
the film after washing is to impinge a blast of air on both sides of the 
film. Pneumatic squeegees for accomplishing this are in general use 
on processing machines but they have not been adopted by labora- 
tories using the rack and tank system of development, owing to the 
non-adaptability of the conventional squeegee for this purpose. 

A simple air squeegee having a single pair of air nozzles was first 
constructed and this produced good results but it did not permit of 
loading the film on the drying reels sufficiently rapidly. The appar- 
atus was modified by adding a second pair of nozzles working at right 
angles to the first set and at a distance of about 6 inches away which 
permitted the film to travel at twice the speed. 

A plan of the apparatus is shown in Fig. 1. The wet film first 
passes over a short wiping table T over which a wad of wetted absor- 
bent cotton wrapped around the film is held so as to loosen any dirt 
adhering to the film. After passing over the idler roller i^i the film 
passes between the first pair of air nozzles iVi, over roller R2 and be- 
tween the second pair of nozzles N2 and then over roller i^3 to the 
drying reel. Rollers Ri, R2, and 7^3 are necessary in order to keep the 
film taut between the nozzles, otherwise any variation in the air 
pressure on the two sides causes the film to vibrate so that there is 
danger of the gelatin coating touching the nozzles which would 

* Research Laboratory, Eastman Kodak Company. 


Pneumatic Film Squeegee — Crabtree & Ives 


produce scratches. The roller Ri consists of two narrow soft rubber 
discs bearing on the perforations and held down by a light tension 
spring. This prevents the film jumping off the roller or backing down 
when threading the machine. It is convenient to turn on the air 
pressure by means of a trigger, otherwise the air flow interferes with 
the threading. 


Rollers Ri, R2, and R3 are shown in section at A, Fig. 1. The 
emulsion side of the film is in contact with rollers R2, and R4 but 
only over the perforation area. A section of the nozzles iVi and iVz 
is shown at B and of the roller RiSit C. A photographic elevation of 
the squeegee is shown in Figs. 2 and 3. 

The rollers and air nozzles are assembled on an aluminum plate 
in the relative positions shown in Fig. 1 which is drawn to scale. 

The Air Nozzles 
Careful adjustment of the air nozzles is necessary to insure 
efficient removal of the water. An angle of inclination of about 40° 
to the film was found satisfactory with a 1/32 inch slit, an air pressure 
of 20-30 pounds per square inch, and a separation of 1/8 inch between 
the nozzles and the film. 


Transactions of S.M.P.E., August 1927 

Air is supplied to the nozzles by means of a four way junction 
from a main supply distributed through pressure rubber tubing, 
Fig. 3. A pressure regulator should be inserted in the air line so as to 
insure uniform performance of the squeegee. 

Manipulation of Squeegee 

Although it is possible to hold the squeegee before the drying 

reel if two persons are employed for the film transfer, it was found 

preferable to suspend the apparatus from a pulley traveling along a 

wire cable stretched in front of the drying reels as shown in Fig. 4, 

Fig. 2 

which clearly indicates the method of use. It is necessary to maintain 
a free loop of film between the rack and the squeegee and to maintain 
a constant speed of rotation of the drying reel during loading, which 
must be slower than during drying. With two persons employed for 
loading the reel speed can be regulated by hand, but with one operator 
it is necessary to control the speed of the reel by means of a foot brake. 
The precise braking mechanism required depends on the nature of the 
reel drive. Usually a band brake fitting over a drum attached to the 

Pneumatic Film Squeegee — Crahiree & Ives 


reel axle and actuated by a foot lever will suffice. The operator must 
unwind the film rack, progress the squeegee along the drying reel, and 
control the drying reel speed simultaneously, but this can be accom- 
plished with a little practice. 

Rate of Drying of the Film 
With the above mentioned air pressure and nozzle adjustment, 
the water is thoroughly removed with the film passing through the 

Fig. 3 

machine at a speed of 2 feet per second. When running at higher 
speeds it is necessary to increase the air pressure, but this increases 
the propensity of the film to vibrate rapidly between the nozzles, thus 
increasing the possibility of scratching. About 2 minutes are there- 
fore required to transfer 200 feet of film to the drying reel. While 
this is somewhat longer than is required for this operation without the 
use of an air squeegee, no later wiping is required, while the drying 
time is shortened because drying is welF under way when the film 
reaches the drying reel. With ordinary methods drying is retarded 
where the film passes over the reel slats because the latter were wetted 
during transference of the wet film from the rack. 


Transactions of S.M.P.E., August 1927 

Fig. 4 

Measurements of the drying times for motion picture positive 
.film at a temperature of 75°F and relative humidity 70 per cent with 
cotton wiping and air squeegeeing were as follows: 

Pneumatic Film Squeegee — Crahtree & Ives 


Cotton Wiping 



Time for loading reel 

2 min. 

3 min. 

Time for wiping film 

2 " 


Time for dr>dng 

19 " 

16 min. 

Time for polishing film 

2 " 


Thus, a 25 per cent saving of time is effected by the use of the air 
squeegee, while subsequent polishing of the film is unnecessary. 

The Air Supply 
Air from a mechanical blower usually contains fine particles of 
oil in suspension. It is very necessary that the air supply should be 

A«v Supp^ 

To Machine. 




Air FIL-ter 

Fig. 5 

entirely free from oil, otherwise drops of oil on the film prevent the 
emulsion from drying and cause crater-hke markings on the surface 
which may be ferrotyped due to contact with the film base when 
wound in the roll. They may be prevented by filtering the air supply 
thoroughly. A satisfactory filter for this purpose is shown in Fig. 5. 
This consists of a metal cyHnder about 18 inches long and 9 inches in 

276 Transactions of S.M.P.E., August 1927 

diameter fitted with a coarse brass wire screen top and bottom and 
packed with absorbent cotton. This fits inside an outer casing the 
details of which are clearly illustrated. The cotton should be renewed 
at frequent intervals and the filtered air supply tested before com- 
mencing work by placing a moistened cloth over the air nozzles for 1 
minute. Any discoloration of the cloth indicates that the air has not 
been efficiently filtered. 

In some cases two or more filters arranged in series may be nec- 
essary to completely free the air from oil. 

1 Trans. Soc. M. P. Eng. 17, 29, 1923; also Brit. J. Phot. 1924 71, 6, et. seq. 

2 Trans. Soc. M. P. Eng. 16, 163, 1923; also Le Phot. 1924 11, 89, et. seq. 

Copies of previous issues of the Transactions that are still 
available may be obtained on application to the secretary, Mr. 
L. C. Porter, Fifth and Sussex Streets, Harrison, New Jersey. 

Nos. 1, 6, and 9 are out of print. The prices of the others are 
as follows : 

Nos. 2 to 8, $0.25 each; Nos. 10 to 15, $1.00 each; Nos. 16, 
17, 18, $2.00 each; Nos. 19 to 28, $1.25 each. 

The supply of some issues is limited. 

The Board of Governors decided that a file of the Transactions 
should be bound and placed in the custody of the Secretary. An- 
other bound file was to be placed in the library of the Engineering 
Society. It was found, however, that no copies of Nos. 1, 6 and 9 
w^ere among the back numbers in the possession of the Society, and 
an appeal was made at the Spring meeting for copies of the same. 
Two copies of Nos. 6 and 9 have since been presented to the Soeiety 
and it is earnestly hoped that two copies of No. 1 may also be ob- 
tained. Should any member have surplus copies, or does not 
place great value on his copy of this issue, the Society will grate- 
fully receive the same. 


J. I. Crabtree and H. C. Carlton* 

IT IS necessaiA^ to clean motion picture film at various stages in 
its progress from the laboratory to the theatre to remove: 

1. Dirt on the base side of negative or positive film; 

2. Dirt or grease which may accumulate on negative film during 
printing ; 

3. Dirt and oil which accumulates on positive film during projection. 

1. AATien processing in the laboratory by the reel and tank 
system, if all excess water is not removed from the film pre\'ious to 
drying, any dissolved salts present in the water supply remain on the 
film after evaporation of the water. The residual salts are usually 
only visible on the base side of the film because on the emulsion side 
they have an opportunity to diffuse within the gelatin coating during 

It is necessary to clean the back of the dried film either by wiping 
with a damp chamois while on the dr^dng reels or by passing the film 
through a cleaning machine. Such treatment is unnecessary in the 
case of positive film if all excess water is removed previous to placing 
on the drying reel by thorough wiping or squeegeeing. 

In the case of negative film it is customary to wind it with the 
emulsion side downward onto a wooden drum covered wdth cloth 
when the base side may be cleaned without danger of injuring the 
image. The cloth should be removed from the drum at frequent 
intervals for cleaning. 

A suitable cleaning liquid for the above purpose should possess 
the following properties: 

(a) It should be capable of dissolving traces of inorganic salts 
and should also dissolve or emulsify grease and mineral oil; 

(b) It should be sufficiently volatile and should not cause the 
gelatin side of the film to swell in a period of several seconds if it 
accidentally has access to it; 

(c) The liquid should not affect the physical properties of film 
with safety or nitrate base or remove the color from film with tinted 

A suitable mixture fulfilhng the above conditions is the following : 

* Research Laboratory, Eastman Kodak Company. 


278 Transactions of S.M.P.E., August 1927 



Ammonia (cone.) 

5 cc. 

2/3 oz. 


95 cc. 

12 oz. 

Denatured alcohol (see below) to make 

1000 cc. 

1 gallon 

The ammonia serves to emulsify any traces of grease or oil, while 
the mixture contains sufficient alcohol to prevent dangerous swelling 
of the gelatin if any of the mixture reaches the emulsion side of the 

A choice of several alcohols for preparing the above liquid is 
available as follows: 

Grain alcohol (ethyl alcohol). This is the most satisfactory for 
the purpose since it has a minimum effect on the film base. 

Denatured alcohol. Ethyl alcohol is available containing a variety 
of denaturants. The most common denaturant is wood alcohol which 
dissolves nitrate film base so that this should be avoided if possible. 

The most commonly available denatured alcohol is motor 
alcohol. The "Pyro" brand of the Industrial Alcohol Company is 
prepared according to the following formula No. 5 of the U. S. 
Internal Revenue Bureau: 

Ethyl alcohol 100 volumes 

Wood alcohol 2 volumes 

Pyridin bases 0.25 volumes 

Kerosene 0.5 volumes 

On diluting this with water the alcohol turns milky owing to 
the kerosene coming out of solution. Kerosene has no effect on the 
film base or gelatin coating and serves to dissolve grease. Although 
pyridin and wood alcohol attack the film base when pure, in the 
above concentration and when diluted with water in the above 
formula they have no harmful effect on the film base during the time 
required for cleaning. The above cleaning liquid prepared with 
"Pyro" motor alcohol had only a sHght tendency to produce curl 
on fihn with nitrate or acetate base after complete immersion for 
24 hours at 70°F. 

Isopropyl alcohol. This is now available commercially and the 
"practical" grade is satisfactory for the purpose. It does not turn 
milky on mixing with water and has little or no curhng effect on 
film with either nitrate or acetate base even on immersion for several 
hours. It is non-poisonous,^ is not decomposed on exposure to fight 
and when used in the above mixture does not attack the silver image 
or the gelatin coating. 


Cleaning Liquids — Crahtree & Carlton 279 

Tertiary hutyl alcohol is also available commercially and has 
properties similar to those of isopropyl alcohol. Its odor, however, 
is somewhat objectionable. 

All the above alcohols tend to remove more or less of the tint 
from nitrate or safety tinted base film but the water present in the 
above cleaning liquid greatly retards this action. 

The precise effect of cleaners prepared with the various alcohols 
on the tinted base is shown in the following table. Samples of film 
were immersed in the cleaners and the times required for visible signs 
of removal of the color were observed. 

Effect of Film Cleaning Liquids on Tinted Base Film 

Formula Safety Base Nitrate Base 

Ammonia (cone.) 5 cc. Liquid sHghtly Same as safety 

Water 95 cc. colored in 10 base 

Motor alcohol to 1000 cc. minutes 

onia (cone.) 

5 cc. 

No effect in 2 Liquid sHghtly 


95 cc. 

hours colored in 10 

opyl alcohol to 

1000 cc. 


Ammonia (cone.) 5 cc. Slight effect in No effect in 16 

Water 95 cc. 1 hour hours 

Tertiary butyl alcohol to 1000 cc. 

The propensity of the cleaner to remove the tint varied with 
different colored bases but the above table gives data for the base 
which was most readily attacked. Since the period of application of 
the cleaning hquid is very much shorter than that required to visibly 
affect the tinted base, the cleaners are considered satisfactory. 

2. When making positive prints from negative film, the negative 
accumulates more or less dirt, grease, and loose particles of dust 
which must be removed at frequent intervals. In any case it is 
advisable to remove dust after every third or fourth passage through 
the printer by passing through silk plush (cut on the bias) moistened 
with a suitable cleaning hquid as the film is being wound on a re- 
winder. More thorough cleaning of the emulsion side can be effected 
by winding the film base side downward on a cloth-covered drum 
as above. 

The requirements of a suitable cleaning liquid for this purpose 
are similar to those for positive film dealt with below. 

3. Positive film accumulates more or less dirt and oil during its 
passage through the projector which causes spots and patchiness on 

280 Transactions of S.M.P.E., August 1927 

the screen. In this connection film which has been toned has a greater 
tendency to show oil spots than untoned film, which is presumably 
a result of the matte surface produced by certain toning processes. 
The oil and dirt may be effectively removed from the film by im- 
mersing in a suitable oil solvent, with or without scrubbing, and then 
removing the excess solvent by squeegeeing and buffing. A satis- 
factory machine for this purpose has been described by Faulkner.^ 
A less satisfactory method of applying the solvent is by means of 
silk plush as the film is being wound on a re winder. 

Various liquids have been suggested for the above purpose but 
the precise effect of such liquids on the film base and on the image, 
so far as is known to the authors, has not been investigated. More- 
over, in certain cases deterioration of the film image has been 
definitely traced to the use of unsuitable chemicals. An investigation 
to determine the most suitable liquids for the above purpose therefore 
seemed desirable. 

Requirements of a Suitable Film Cleaning Liquid 

A suitable film cleaning liquid should possess the following 
properties : 

1. It should readily dissolve fats and mineral oils; 

2. It should not affect the gelatin coating or the film base, or 
remove the color from film with tinted base. Also it should not attack 
the silver image or a tinted or toned image even on prolonged contact 
in the presence of moisture, because when cleaning on a re winder 
any excess of solvent which does not evaporate is trapped between 
the convolutions of the film, when it can evaporate only very slowly; 

It should also not decompose on exposure to light to give 
products which are injurious to the film; 

3. The boiling point and latent heat of vaporization should be 
such as to permit of sufficiently rapid drying; 

4. It should be non-combustible, non-toxic, and be readily 
available at a reasonable price. 

At the outset a survey was made of all the possible commercially 
available non-inflammable and inflammable oil solvents, and the 
most promising of these were investigated as follows. 

Non-inflammable Oil Solvents 

" The following compounds were selected by virtue of their suit- 
able volatility, solvent action, and price: 

Cleaning Liquids — Crahtree & Carlton 281 



Boiling Point 










Ethylene dichloride 



Carbon tetrachloride 



The effect of these compounds on the fihn was 

investigated as 

follows : 

Effect of N on-Inflammahle Solvents on Motion Picture Film 

The effect of the above solvents on film was studied by placing 
a strip of developed positive motion picture film (nitrate base) in a 
100 cc. stoppered bottle with 40 cc. of the solvent and 3 cc. of water 
at room temperature. The film was thereby subjected both to the 
liquid and its vapors . Any tendency of the film to curl or of the image 
to change color was observed after 18 hours with the following results: 

Conditio?! of Film {nitrate base) 
Solvent after 18 hours at 70°F. 

Dichlorethylene (pure E.K.Co.) Slight curl when wet. Bad curl 

when dry. No effect on image. 
Trichlorethylene (Com.E.K.Co.) No effect on film base. Emulsion 

softened and image obliterated. 
Trichlorethylene (pure E.K.Co.) No effect on image or film base. 
Tetrachlorethylene (Dow) Slight curl when dry. No effect 

on image. 
Ethylene dichloride (pure E.K. Bad curl. No effect on image. 

Carbon tetrachloride (Dow) No effect on base or emulsion. 

Carbon tetrachloride (pure E.K.) No effect on base or emulsion. 

Any curling tendency in the above tests was an indication that 
the film base had been attacked. The tests show that dichlorethylene 
and ethylene dichloride exert a solvent action on the base, while 
commercial trichlorethylene affects the gelatin coating and the 
image; these liquids are therefore unsuitable. Further tests were 
made with pure trichlorethylene, tetrachlorethylene, and carbon 
tetrachloride at 95°F. as follows: 

282 Transactions of S.M.P.E., August 1927 

Effect of Non-Inflammable Solvents on Motion Picture Film at 95° F. 

Solvent Condition of Film {nitrate base) 

Trichlorethylene (Roessler & No effect on base. Image turned 

Hasslacher) slightly brown in four days. 

Tetrachlorethylene (Dow) Image attacked at surface of liquid 

at end of four days. 
Carbon tetrachloride (Dow) Started to curl at end of six days. 

No effect on image. 
Carbon tetrachloride (pure E.K. Started to curl at end of eight 

Co.) days. No effect on image. 

Carbon tetrachloride (taken from Film curled at once and turned 
fire extinguisher) brown above liquid at end of 

three days. 
Any effect of the above solvents on the image was attributed to 
decomposition in the presence of water with the liberation of hydro- 
chloric acid. A sample of old tetrachlorethylene which was strongly 
acid was treated with anhydrous sodium carbonate which would 
remove any acid present, and this sample had no effect on the image. 
Another acid sample was treated with anhydrous calcium chloride 
to remove water but this affected the image showing that hydrogen 
chloride when dissolved in the solvent and in the absence of water 
will attack the image. To confirm this, dry hydrogen chloride was 
passed into pure dry carbon tetrachloride. The resulting liquid 
attacked the silver image bleaching it to white silver chloride. 

The above tests indicated that of the solvents tested, carbon 
tetrachloride is the most resistant to decomposition by heat and 

Effect of Light on Solvents, 
Since on storage, solvents are subjected to the action of Hght, 
the effect of exposure to light on the rate of decomposition was 
studied. In order to secure an accelerated effect, the solvents were 
exposed in open bottles in the presence of moisture to a quartz 
mercury vapor lamp for from 5 to 30 hours. Strips of film were then 
immersed in the hght exposed solvents for varying times and any 
effect on the base or silver image was observed. 

The acidity of the sam^ples was also determined by adding an 
equal volume of water, shaking thoroughly, and titrating with dilute 
normal caustic soda. As shown by the following table, the effect 
on the film image was roughly proportional to the quantity of hy- 
drochloric acid present. 

Cleaning Liquids — Crahtree & Carlton 


Effect of Light on Solvents at 70"^. 

Time of 

Exposure to 



(cc. N/10 

Nature of Solvent 

Vapor Lamp 





0.12 cc. 

Slight curl. No effect 

(Roessler & 

on image in 10 




5 hours 

1.10 cc. 

Film badly curled. 

(R. & H.) 

Image bleached 
in 2 days. 



0.12 cc. 

No effect on film in 

(R. & H.) 

10 days. 


5 hours 

0.65 cc. 

Image destroyed in 

(R. & H.) 

2 days. 

Carbon tetrachloride 


0.09 cc. 

No effect in 10 days. 

(R. & H.) 

Carbon tetrachloride 

31 hours 

0.09 cc. 

Image turned brown 

(R. &H.) 

in 10 days. 

The above results show that trichlorethylene and tetrachlor- 
ethylene under the influence of violet light and moisture undergo 
decomposition. The compounds are probably oxidized to phosgene 
(COCI2) which is decomposed by moisture to form hydrochloric 
acid and carbon dioxide as represented by the following equations. 

C2CI4 +02= 2COCI2 

tetrachlorethylene oxygen phosgene 

COCI2+H2O = 2HC1 + CO2 

phosgene water hydrochloric acid carbon dioxide 

The hydrochloric acid formed attacks the gelatin causing it to 
soften, and likewise converts the image to silver chloride. The 
extreme toxicity attributed to old or impure samples of compounds 
of this type is undoubtedly due to the presence of phosgene. 

Of the non-inflammable compounds tested, carbon tetrachloride 
most nearly approaches the ideal film cleaning liquid as outUned 
under the above list of requirements. It is especially valuable since 
when pure it does not readily decompose under the influence of light 
to form compounds which are injurious to the film. However, in 
order to prevent any possible decomposition on storage, it should be 
kept in brown bottles or opaque containers. 

284 Transactions of S.M.P.E., August 1927 

Inflammable Film Cleaning Liquids. 

In addition to non-inflammable solvents, a survey of possible 
inflammable liquids was also made because it was considered that 
in the event that an otherwise suitable liquid in this classification 
was discovered, its objectionable inflammability might be partly 
overcome by admixture with carbon tetrachloride. 

The only promising solvents under this classification were ben- 
zene, toluene, xylene, gasoline and allied petroleum distillation pro- 
ducts. Tests with these compounds, similar to those made with the 
non-inflammable compounds above, showed that none of the solvents 
affected the silver image, but benzene and toluene caused film with 
nitrate and acetate base to curl after immersion for 2 days at 70°F. 
All these solvents evaporate more slowly than carbon tetrachloride 
which in some cases may be desirable. 

It was considered that possibly these compounds might be con- 
siderably less toxic than carbon tetrachloride, in which case it would 
be desirable to use them with the addition of only sufficient of the 
tetrachloride to remove danger of explosion. 

Toxicity of Benzene, Gasoline, and Carbon Tetrachloride. 

Although no practical toxicity tests were made with the solvents 
under investigation, adequate information is to be found in the 
literature. Tests with animals have shown that benzene, gasoline, 
and halogen substitution products of the hydrocarbons such as 
carbon tetrachloride all produce varying stages of poisoning resulting 
in dizziness and unconsciousness, and finally death. 

Lehmann^ found that with cats, air containing 20 to 30 mg. per 
liter of benzene causes loss of consciousness in a few hours and 42 
mg. per liter produced death. Hamilton^ quotes a large number of 
cases of benzene poisoning in industry, some of which resulted in 

Haggard^ experimented with dogs and found that the toxicity 
of gasoline was about one-half that of benzene. 

Lehmann,^ working with rabbits, found that 240 mg. per liter 
of carbon tetrachloride were necessary to produce death in two hours. 
Although no data were found giving a direct comparison between the 
toxicity of carbon tetrachloride, benzene, and gasoline, a survey of 
the experiments of Haggard and Lehman n indicates that carbon 
tetrachloride is less toxic than benzene and slightly more toxic than 
gasoline though this depends on its purity. Few cases of industrial 

Cleaning Liquids — Crabtree & Carlton 285 

poisoning by carbon tetrachloride have been recorded and these 
deaths were probably due to the use of an impure product which 
may have contained an excess of phosgene and hydrogen chloride. 
Since the presence of 3 to 5 mg. per liter of carbon tetrachloride 
imparts a strong odor to the air, there is no excuse in practice for 
the concentration approaching the danger point, which is 10 times 
this concentration. 

The Suitability of Carbon Tetrachloride for Cleaning 
Motion Picture Film. 

The above experiments indicate that carbon tetrachloride when 
pure is quite satisfactory for cleaning motion picture film. It is a 
good solvent for oils and fats, evaporates readily, is non-combustible, 
and is readily available at a reasonable price. It does not affect the 
image even on prolonged contact and has a minimum tendency to 
decompose on exposure to light in the presence of moisture. Although 
toxic when impure, the pure compound is no more toxic than benzene 
and if reasonable ventilation is provided, it may be used with relative 

Tests also showed that carbon tetrachloride has no curling effect 
on film with nitrate or safety base after two days and it does not 
remove the color from either nitrate or safety film with tinted base. 

Manufacturers such as the Dow Chemical Co. and the Eastman 
Kodak Company supply sulphur-free carbon tetrachloride which is 
satisfactory for cleaning film. A few years ago many commercial 
samples of tetrachloride contained sulphur chloride which was formed 
as a by-product in its manufacture by the action of chlorine on 
carbon disulphide. On exposure to the air in the presence of moisture 
sulphur chloride deposits sulphur which is capable of combining with 
the silver image to form yellow silver sulphide. Such samples of 
carbon tetrachloride containing sulphur chloride when left in contact 
with motion picture film attacked the image, especially in the presence 
of moisture, and bleached it out to a faint yellowish-white image of 
silver sulphide. No such commercially impure samples of carbon 
tetrachloride have been encountered within the past two years. 

Mixtures of Carbon Tetrachloride with Inflammable Solvents. 

In some laboratories and exchanges a mixture of carbon tetra- 
chloride with high test gasoline is used for film cleaning. This mixture 
evaporates less readily than pure tetrachloride which may be an 
advantage in some cases. Its adoption in the past was a result of the 

286 Transactions of S.M.P.E., August 1927 

toxicity of impure samples of tetrachloride, a 50% mixture by volume 
with gasoUne reducing this considerably. This mixture burns with 
great difficulty and is satisfactory from a fire hazard standpoint 
although the proportion of the two liquids necessary to give a non- 
inflammable mixture depends on the nature of the gasoHne. It is 
considered that pure carbon tetrachloride is to be preferred to such 
a mixture for general purposes. 

Film Moistening Liquids. 

In addition to accumulating oil during projection, both the 
film base and gelatin coating lose moisture and tend to become brittle 
owing to the excessive heat to which the film is subjected. If the 
film were allowed to cool to room temperature between successive 
projections, little trouble would be encountered, but in practice the 
film does not cool off sufficiently between successive projections and 
the resulting baking process drives out the moisture, which results 
in brittleness. 

If film which has been rendered brittle in this manner is exposed 
to a moist atmosphere even for only a relatively short time it tends 
to regain its flexibility. It is not possible to do this by placing the 
tightly wound reels of film in a humidor or a vessel containing water 
because the moisture penetrates the convolutions of film very slowly. 
It would be possible to humidify the film satisfactorily by passing it 
continuously through a humid chamber or by winding the film in 
contact with a damp strip of paper or other absorbent ribbon. Such 
a system however, is inconvenient in the theatre or exchange. 

A satisfactory method of moistening film is to immerse it in a 
mixture of water and a water-miscible volatile liquid such as grain 
alcohol. The percentage of water to be used in the mixture depends 
on the degree of brittleness of the film and the time which elapses 
between application and evaporation of the liquid. If an application 
machine of the Dworsky^ type is used, this depends on the rate 
of passage of the film through the machine. During this short 
period Uttle or no swelling of the gelatin coating occurs, but sufficient 
moisture is absorbed to restore the flexibility of the dried out gelatin 
coating. Moreover, when the film is wound up in a roll, the dried 
out film base can also absorb moisture by virtue of being in contact 
with the moistened emulsion. Fihn base absorbs moisture relatively 
slowly so that little or none is absorbed by it in the period of apph- 
cation of the moistening liquid. 

Cleaning Liquids — Crahtree & Carlton 287 

At the outset a survey was made of possible water-miscible 
volatile liquids which could be used for the purpose. The require- 
ments of such a liquid are identical with those for the film base 
cleaning liquid already outlined. A choice of the following liquids 
is possible; grain alcohol, denatured alcohol, isopropyl alcohol, 
and tertiary butyl alcohol. 

The exact quantity of water to be added to the alcohol must be 
determined by trial. From 15 to 25 per cent water is usually satis- 
factory and this proportion holds in the case of all the alcohols 
named above. The condition of the film after treatment will indicate 
any necessary changes in the proportion of water to be added. If 
it is too tacky less water should be used and if too dry and brittle 
the quantity should be increased. 

A mixture of either of the above alcohols with water has little 
or no solvent action on mineral oil which may be present on film 
after projection. However, in practice the rubber squeegees in the 
Dworskyi machine tend to emulsify and remove traces of oil. If 
much oil and dirt is present on the fihn a moistening Hquid which 
is also capable of dissolving oil must be used. 

Combined Cleaning and Moistening Liquids 
It is possible to incorporate a mineral oil solvent such as carbon 
tetrachloride with any of the above alcohol-water mixtures. The 
quantity of carbon tetrachloride which can be added depends on 
the quantity of water present in the alcohol. For example: tertiary 
butyl alcohol and carbon tetrachloride, and water and tertiary butyl 
alcohol are miscible in all proportions. Water and tetrachloride 
are immiscible, but if water is gradually added to a mixture of the 
alcohol and carbon tetrachloride with shaking, a uniform mixture 
is obtained until a critical quantity of water has been added, beyond 
which the mixture turns milky and the hquid separates on standing 
into two phases or separate layers. The quantity of water which 
'V given mixture of the alcohol and carbon tetrachloride will hold 
depends on the alcohol content and on the temperature, the mixture 
holding less water at lower temperatures. 

A curve showing the limiting quantity of water which can be 
added to mixtures of tertiary butyl alcohol and carbon tetrachloride 
in varying proportions is given in Fig. 1. Commercial samples of 
the alcohol are apt to contain varjdng quantities of water. The 
data are for a practical grade of tertiary butyl alcohol which was 
practically anhydrous. 


Transactions of S.M.P.E., August 1927 

The miscibility curves for grain alcohol, denatured alcohol, 
isopropyl alcohol, and tertiary butyl alcohol are approximately 
identical for all practical purposes. For the preliminary experiments 
the following formula was used as a cleaner: 

Water 15 parts by volume 

Carbon tetrachloride 20 " " " 
Alcohol to make 100 " " " 

Of the cleaning liquids prepared according to the above formula 
the one containing denatured or grain alcohol had little or no solvent 

90 - 


O 70 






< 30 







9 12 15 18 

Fig. 1 - 



properties for mineral oil so that it had no advantages over a plain 
alcohol-water mixture. When prepared with isopropyl alcohol the 
mixture dissolved 1 per cent of light machine oil and with tertiary 
butyl alcohol about 3 per cent of oil. Since the quantity of oil on 


Cleaning Liquids — Crahtree & Carlton 


dirty film is never such that the concentration of oil in the cleaning 
fluid would exceed this, the isopropyl and tertiary butyl mixtures 
were considered promising. 

In order to determine the effect of the above mixtures on the 
film, strips of safety and nitrate motion picture film with plain 
and tinted bases were immersed in glass bottles containing the 
various liquids and stored for several days at 70°F. The results 
obtained were as follows: 

Effect of Cleaning and Moistening Liquids 
on Motion Picture Film at 7-0° F . 

Effect on Effect on Gela- Effect on 


Film Base 

tin Coating 
and Linage 

Tinted Base 

Water 15 cc. Acetate 
CCh 20 cc. Shght curl 

Isopropyl Nitrate 

alcohol Shght curl 

to 100 cc. in 20 hours 

Changed silver 
image to white 
silver chloride 
in 20 hours 

Slight solvent 
action in 5 min. 


CCI4 10 cc. 

Ter. butyl 


to 100 cc. 

20 cc. Acetate 

Slight curl 
in 20 hours 

No effect in 
20 hours 

No effect on Acetate 
image Slight solvent 

action in 
20 min. 

No effect in 
60 min. 
In the case of the isopropyl alcohol mixture an interaction 
between the alcohol or possibly an oxidation product of this and 
the tetrachloride occurred causing the hberation of hydrogen chloride 
which attacked the silver image, converting it to silver chloride. 
Although neither isopropyl alcohol nor carbon tetrachloride when 
used alone attacked the silver image, on mixing the two in the 
presence of water and adding a little silver nitrate solution, a white 
precipitate of silver chloride formed within a period of a few minutes. 
No such action occurred with tertiary butyl alcohol. 

The interaction of the alcohols with carbon tetrachloride in 
the presence of water was investigated further by exposing mixtures 
prepared with the different alcohols to ultra-violet light. In the 
case of mixtures of tetrachloride and water with denatured alcohol 

290 Transactions of S.M.P.E., August 1927 

and isopropyl alcohol, the image was attacked in 8 hours. No effect 
was obtained with a mixture containing tertiary butyl alcohol after 
exposure for 24 hours. 

Of the combined cleaning and moistening Hquids tested, the 
following was the most satisfactory: 

Carbon tetrachloride 10 parts by volume 

Water 20 « " 

Tertiary butyl alcohol to 100 " " " 

This has no harmful effect on the film, it dissolves a sufficient 
quantity of mineral oil and it humidifies the gelatin coating. If 
it is necessary to increase the quantity of water in the formula, 
the proportion of the ingredients to give a clear solution is indicated 
by the miscibility curve in Fig. 1. 

The capacity of the unused Hquid for dissolving mineral oil is 
limited, but with use the Hquid will dissolve a greater proportion 
of oil as a result of dehydration of the liquid by virtue of the absorp- 
tion of water by the gelatin coating of the film. Unless the Hquid is 
used for long periods it is usually not necessary to add a further 
quantity of water to compensate for that absorbed by the film. 

If the film to be cleaned is coated with an excess of oil the 
above solution may not entirely remove all the oil with one treat- 
ment and a second treatment may be necessary. 

Experiments have been made with the additions of glycerine 
and ethylene glycol and mixtures of these to the above solution but 
the results indicated that these are usually not necessary. 

An alternative method of moistening the film is to first remove 
the oil with carbon tetrachloride and then give the film a second 
treatment with a mixture of denatured alcohol or tertiary butyl 
alcohol and water in the proportions outlined above. This involves 
more labor but is a very satisfactory procedure. 

Practical Recommendations. 
1. For cleaning the base side of negative and positive film 
after processing the following solution is recommended : 
Ammonia (cone.) 5 parts by volume 

Water 95 " " 

Alcohol* to make 1000 " " " 
* The "Pyro" brand of denatured alcohol of the Industrial Alcohol Com- 
jpany is satisfactory, although isopropyl alcohol or tertiary butyl alcohol are to 
be preferred. 

Cleaning Liquids — Crabtree & Carlton 291 

The solution may be applied to positive film by means of a 
cleaning machine and to negative film when wound face down onto a 
cloth covered drum. Negative film may be cleaned with safety on 
certain types of sprocketless cleaning machines, but it should not 
be handled on machines fitted with sprockets owing to the possi- 
bility of damage to the film. 

2. In order to remove dust and finger markings from negative 
film it should be cleaned before printing by wiping gently with 
silk plush moistened with carbon tetrachloride (sulphur-free) as it 
is being wound on a re winder. An electric fan should be arranged 
so as to blow a current of air across the film in a direction away 
from the face of the operator. The cleaning process should be re- 
peated after every third or fourth print has been made. 

3. For cleaning film which has accumulated oil and dirt during 
projection, carbon tetrachloride (sulphur-free) as supplied by the 
Dow Chemical Co., is recommended. For cleaning brittle film the 
following solution at the same time removes oil and moistens the 
film thus tending to restore its flexibility. 

Carbon tetrachloride 10 parts by volume 

Water 20 " " 

Tertiary butyl alcohol to make 100 " " " 

The quantity of water in this formula should be varied accord- 
ing to conditions. If the film is too moist after treatment less water 
should be used in the formula and if too brittle more water should 
be added. In this case it will be necessary to increase the quantity 
of alcohol also so as to retain the water in solution. 

The cleaning liquid may be applied to the film in the same 
manner as outlined under (2) above. This method is not always 
satisfactory because if the solvent does not evaporate thoroughly 
before the fihn is rewound, more or less solvent is retained between 
the convolutions of the film and in case an impure solvent is used 
this will be liable to attack the film image on storage. A film cleaning 
machine of the type recommended by Faulkner^ is to be preferred. 

In the case of very brittle film two successive applications may 
be necessary. The odor of tertiary butyl alcohol may also be objec- 
tionable in hot weather. 

An alternative procedure is to first remove oil from the film 
with pure carbon tetrachloride and then moisten the film by passing 
through a mixture of denatured alcohol, isopropyl alcohol, or tertiary 
butyl alcohol with 15 to 25 per cent of water. 

292 Transactions of S.M.P.E., August 1927 

Although air which contains sufficient carbon tetrachloride to 
smell perceptibly is not dangerously toxic, ample ventilation should 
be supplied when using this or any other solvent. In the case of a 
film cleaning machine, a suitable exhaust hood with carry-off pipes 
should be arranged over the machine. 

Carbon tetrachloride as received in drums often contains a 
small quantity of water in suspension as fine droplets. Unless the 
water is removed before use, spots will be left on film after cleaning 
as a result of local swelling of the gelatin by the water. 

The water can be removed readily by pouring the Hquid through 
a vertical glass tube containing granules of anhydrous calcium 
chloride. A tube 4 or 5 feet long, 3 or 4 inches wide, and fitted 
with an outlet tube about one-half inch in diameter is satisfactory. 
A wad of absorbent cotton at the bottom of the tube serves to retain 
the calcium chloride granules. 

To use the column the carbon tetrachloride is poured in at the 
top and allowed to run out at the bottom directly into the dispensing 
bottle which has been dried previously. Several gallons can be passed 
through the apparatus in a few minutes. The calcium chloride should 
be thrown away and replaced occasionally. Usually several hundred 
gallons can be treated with the quantity described above. Both ends 
of the tube should be stoppered when the apparatus is not in use, 
otherwise the calcium chloride will absorb moisture from the atmos- 

1 H. C. Fuller, Chem. & Met. Eng. 29, 538, 1923. 

2 Faulkner, Trans. S. M. P. E. 25, 117, 1926. 

3 H. B. Lehmann, Arch, fiir Hyg. 75, 1, 1912. 

^ "Industrial Poisoning in the U. S." by A. Hamilton (Macmillan). 

5 Haggard, J. Pharmacol & Exp. Therap. 16, 401, 1920. 

6 H. B. Lehmann, Arch. fur. Hyg. 24, 1, 1911. 


Mr. Stewart: When you speak of humidifying brittle film do 
you wish to imply that any of the moisture goes into the film, base? 

Mr. Crabtree: Yes. 

Mr. Stewart: Have you any idea of the moisture content of 
new film? 

Mr. Crabtree: Nitrate film base contains from 1 to 2 per cent 
of moisture. The gelatin coating when in equilibrium with an 
atmosphere at 60-70 per cent relative humidity contains from 10-12 

Cleaning Liquids — Crahtree & Carlton 293 

per cent of water. Dry gelatin absorbs moisture fairly rapidly when 
exposed to a damp atmosphere. However, dried out film base 
absorbs moisture much more slowly and even when totally immersed 
in water, from 20-30 hours are required for the maximum amount of 
water to be absorbed. 

Mr. Stewart: I asked this because some time ago I took a 
pound of celluloid, soaked it for hours and weighed it again and found 
no change in weight. 

Mr. Crabtree: The fact that the celluloid which you used did 
not absorb any water proved that it was fairly saturated. In order 
to make such a test the film should first be baked so as to drive out the 
moisture and afterwards soaked and weighed again. 

Mr. Stewart: It was brittle film. 

Mr. Crabtree : Possibly the brittleness was due to other causes. 

Mr. Lindsay: Does this solution for cleaning and moistening 
evaporate immediately or would a theater have to have a small 
drying cabinet? 

Mr. Crabtree: The film dries immediately. It first passes 
through rubber squeegees and is then wiped with buffers.' When the 
film is wound up the base is in contact with the moist gelatin and 
derives its moisture therefrom. The amount of water absorbed by 
the gelatin coating is not sufl&cient to cause sticking. 

Prof. Wall: Mr. Crabtree said that the first pneumatic squee- 
gee was used by Mr. Kelley. We fitted one up in Florida in 1917. 
We had two water sprays to take the grit off the film, then two strips 
of chamois to take the water off, after which the film passed between 
the nozzles of the pneumatic squeegee. We had three of these at a 
distance of about 18 inches and found them extremely efficient. 

Mr. Crabtree: That is different. The apparatus which Mr. 
Kelley used was the first which I know of which was used to dry film 
during transference by hand from a developing drum to a drying reel. 
The conventional pneumatic squeegee as used on continuous machines 
when used for this purpose is apt to damage the film. 


P. M. Rainey* 

VITAPHONE is a trade name applied to one method of making 
and reproducing sound motion pictures. By sound motion 
pictures we mean the reproduction of scenes in proper timed relation 
with the reproduction of the natural sounds accompanying the scene 
or with other sounds designed to produce a desired effect. The 
sounds may be spoken words, vocal or instrumental music or some 
form of noise, such as the roar of a passing train, the crash of real or 
artificial thunder, the squeak of a wheel, the buzz of a bee or a saw, 
or in fact any air vibration which the ear recognizes. The repro- 
duction of scenes in proper timed relation with the sound naturally 
involves the recording of both scene and sound in such a way that 
the proper time relation may be maintained during reproduction. 

You gentlemen are familiar with the limitations of recording 
scenes. You must have certain conditions as regards light intensity, 
focus, etc., otherwise the recording of the scene will not be faithful 
in every detail. In the recording of sounds, there are analogous 
limitations. For example, the sounds to be recorded must be well 
above the intensity level of extraneous sounds. 

The problem of proper time relation between the reproduction 
of a scene and the natural accompanying sounds is most easily solved 
by the simultaneous recording of sound and scene. In the case of 
obtaining the proper time relation between the scene and other than 
the natural accompanying sounds, as for example, incidental music, 
the solution is most easily obtained by recording these other sounds 
in proper time relation with the reproduction of the scene. In either 
case, precaution must be taken against recording undesirable ex- 
traneous noises. For example, the Director's megaphone must be 
dispensed with during recording and noiseless gestures or signals 
used to give the desired cues or instructions. The studio must be 
acoustically suitable with heavily carpeted floors, sound absorbing 
walls, sound damping draperies, etc., in order to prevent undesirable 
echoes or reverberations which otherwise would be recorded with 
detrimental results. 

While we are describing a new art, the conception of sound 
motion pictures is not new. The records of the Patent Offices of the 

* Electrical Research Products Division. Western Electric Co. 


The Vitaphone — Rainey 


civilized world bear evidence that the conception of sound motion 
pictures is more than thirty years old. The advent of the telephone 
in 1876, the phonograph in 1880, and the motion picture in 1895 
appear to have stimulated inventive genius along these lines during 
the closing years of the past century. It appears also that the prac- 
tical realization of this vision like the vision of the long distance 
telephone, radio, transmission of pictures by wire, television, and 
other developments was long retarded by the lack of fundamental 
knowledge concerning the underlying principles involved. Imagina- 
tion has run far ahead of realization. 




Fig. 1. A public address equipment. 

Much has been written about the conquests of the vacuum tube. 
This magic lamp has converted dreams into realizations in the field 
of wire and wireless telephony, and is rendering distinguished service 
in other fields. This powerful new tool, together with the technique 
which was contemporaneously developed with and around the device, 
has made this old dream of sound motion pictures a reality. The 
service rendered by the vacuum tube in connection with sound 
motion pictures is not spectacular in that it renders a new or unusual 
service. It simply performs a function which it has been performing 
in modern telephony, namely, the faithful amplification of sound 
currents. The apparatus, equipments and methods used, and which 
we will describe, are with few exceptions, apparatus and methods used 


Transactions of S.M.P.E,, August 1927 

in telephony, and are similar to those used to permit large audiences 
to hear the words of a speaker present or at a distance. Equipments 
for this purpose are commonly called Public Address equipments. 
Fig. 1 is a schematic diagram of a Public Address equipment. The 
sound waves are picked up by the microphone at the left and con- 
verted into electrical sound currents. The currents then pass to the 
amplifiers where they are amplified sufficiently to operate the loud 
speakers at the right, and give sufficient volume for the purpose of 
the particular installation. The loud speakers convert the electrical 


o/ ^r^\ 

OV Jr\l 








Fig. 2, A schematic diagram of a Vitaphone sound-reproducing equipment. 

sound currents into air vibrations or sound. The degree of ampHfica- 
tion required may be of interest. The electrical energy developed by 
the microphone is of the order of 1 X 10~^ watts, the output of the 
amplifiers which operates the loud speaker^ may be as much as 40 
watts. This means that the amplifiers are giving an energy amplifica- 
tion of four billion. 

With this type of equipment there are no acoustic limitations 
to the size of audience that can be made to hear the voice of a speaker. 
As a matter of fact the only limitations to the size of a congregation 
that can be made to hear a speaker are the limitations of transporta- 
tion and human endurance. 

Fig. 2 is a schematic diagram of a Vitaphone sound recording 
equipment, and a Vitaphone sound reproducing equipment. The 
similarity between these and Fig. 1 should be noted. 

The Vitaphone — Rainey 297 

In making sound records the loud speakers of a Public Address 
equipment are replaced by a recording mechanism in which the 
amplified sound currents effect recording. In the Vitaphone, these 
amplified currents are used to actuate a stylus and effect recording 
in suitable material in the familiar disc form. Experimentally these 
same currents have been used to vary the intensity of light to which 
a photographic film is exposed. In either case the result is the same 
in that a reproducible record is made. 



Fig. 3. Sensitivity-frequency curves of the human ear. 

In the reproduction from sound records the same type of equip- 
ment is used, but instead of replacing the horns by a recorder, the 
microphone or pick-up equipment is replaced by a suitable re- 
producer. This reproducer in conjunction with a record generates 
currents which are amplified and converted into sound by the loud 

Before I describe the apparatus, equipment and methods in 
detail, permit me to review briefly the fundamental requirements 
for faithful recording and reproduction of sound. 

Sound may be defined as air vibrations to which the ear is 
sensitive. These vibrations or variations in air density are harmonic 
or sinusoidal and vary widely in frequency and intensity. The fre- 
quencies occurring in ordinary speech, instrumental music and 
ordinary noises, range from 16 cycles per second to 10,000 cycles per 
second. Higher frequencies than 10,000 are audible, but are in 

298 Transactions of S.M.P.E., August 1927 

general of negligible importance insofar as intelligibility of speech, 
enjoyability of music or the recognition of familiar sounds is con- 
cerned. In this connection it should be borne in mind that the 
human ear has its limitations, and that the response of the ear to 
various frequencies is not the same. Further that these variations 
vary with different individuals. 

Fig. 3 shows audiograms or sensitivity frequency curves of 
twenty women, all possessed of supposedly normal hearing. This 
slide suggests that there is little wonder that it is difficult to please a 
large audience of women with any audible rendition. 

Most sounds are a combination of a large number of frequencies. 
In general we are not interested in sounds consisting of a single 
frequency. Middle "C" on the piano produces a fundamental vibra- 
tion of 256 cycles per second, but in addition produces overtones of 
higher frequencies and of varying intensities. The same note on 
another musical instrument will have the same fundamental fre- 
quency, but the overtones will differ either as regards frequency or 
intensity or both. It is these overtones or timbre, as they are some- 
times called, which mark the distinction between the same note on 
different musical instrum.ents. The character of these overtones 
determines the quality of musical tone and constitutes the ear-marks 
by which voices and sounds are recognized. Faithful recording and 
reproduction must take into consideration the overtones. Faithful 
sound reproduction, therefore, consists in the regeneration of all of 
the fundamental and overtone frequencies with the same intensities 
as they appeared in the original. This means that the microphone, 
vacuum tubes, transformers, recorders, reproducers and loud speakers 
should all have a straight line characteristic, i.e., they must not 
discriminate unduly against any frequency band. They should have 
the same efficiency at all frequencies within the audible band. This 
is illustrated by the requirements controlling the design of a trans- 
former for power transmission or for speech or music transmission 
purposes. The requirements for a good power transformer are in 
general a high efficiency at one frequency, and at full load. The 
efficiency at other frequencies, and at times of light load is of secon- 
dary importance. In other words, a straight line characteristic is 
of little importance in comparison with a high efficiency at one fre- 
quency and at full load. For the transmission of speech or sound 
currents, however, we must have a transformer which has approxi- 
mately the same efficiency over a wide band of frequencies and 

The Vitaphone — Rainey 


variations of load. In fact the uniformity of the efficiency with the 
frequency and load is more important than whether the efficiency 
is high or low. 

The problem of securing a straight line characteristic throughout 
the audible range of frequencies is also made more difficult by the 
fact that the higher frequencies of sound possess much less energy 
than the lower frequencies. The vessel sounds are low-pitched sounds 
with great energy, while the consonants are higher-pitched, and 
possess less energy, hence the suppression of the higher frequencies 
materially affects the intelligibility of speech, and robs music of its 
brilHance. The suppression of the lower frequencies robs speech and 
music of its volume, but has little effect on the intelligibility of 
speech or the brilliance of music. 





2000 JOOO 



Fig. 4. Energy distribution of speech over the audible frequency range. 

Fig. 4 shows the energy distribution of speech over the audible 
frequency range. 

Fig. 5 shows the electrical characteristics of certain electrical 
circuits known as filters. Three types are shown, high pass, low pass 
and band pass filters. By low pass filters we mean filters that offer 
little impedance to low frequency currents and high impedance to 
high frequency currents. By high pass filters we mean the inverse of 
low pass filters. By band pass filters we mean a combination of low 
and high pass filters that suppress all frequencies outside of a certain 

300 Transactions of S.M.P.E., August 1927 . 

band of frequencies. You all remember the story of the eminent 
scientist that had a carpenter cut a small hole for the small cat after 
he had finished a large hole for a large cat. Modern electrical filters 
of the characteristics shown make it appear that this incident may 
have been prophetic rather than foolish. If we call the big cat a high 
frequency and the little cat a low frequency, it is plain that the little 
cat will have as much difficulty in getting through the big hole as 
the big cat will have getting through the small hole. The band pass 
filter shown would then represent a medium size hole for a medium 
size cat. 


. T T T . 


^Hl 1 I I t II— I — ^1-^ 




Fig. 5. Characteristics of electrical filters. 

Filters of this type make it possible to determine the effect of 
various frequencies on the intelligibility of speech. They also make 
it possible to show the effect on musical reproduction when certain 
frequencies are omitted or partially suppressed. Filters are also 
used to correct undesirable characteristics. 

It would have been cumbersome to have brought all of the 
apparatus necessary to demonstrate this phenomena, but we have 
prepared phonograph records which were made with filters which 
serve the purpose of illustration. 

One of these records is a piano selection and the other speech. 
Each record consists of several repetitions with filters as follows: 

1. No filter. Straight line characteristic; 

2. A high pass filter suppressing frequencies below 375 cycles 
per second; 

3. High pass filter suppressing frequencies below 750 cycles; 

4. No filters; 

5. Low pass filter suppressing frequencies above 2,500 cycles; 

The Vitaphone — Rainey 


6. Low pass filters suppressing frequencies above 1,250; 

7. No filters. 

This clearly demonstrates in the case of speech and music that 
the volume of sound rests with the low frequencies, and that the low 
frequencies in speech and music are therefore important. It also 
demonstrates that the higher frequencies are important in speech 
from an intelligibility standpoint, and that they provide the brilliance 
in piano music. High frequencies are, therefore, equally important, 
and the necessity for a straight line characteristic of both recording 
and reproducing is therefore estabhshed. 





tfoo — 



i 60 

I — 

* -»0 


SO lOO zoo 600 1000 eOOO 5000 


Fig. 6. Frequency characteristic of public address amplifiers. 

Fig. 6 shows frequency characteristic of Public Address amplifiers 
with a carbon button transmitter. While this curve is not a straight 
line over the entire range, we are pleased to call it a straight line 
characteristic, particularly since the diversions from the straight line 
are small in comparison with the variations of the human ear as 
indicated above. 

Fig. 7 shows the characteristics of a Condenser Transmitter 
with its ampKfier plotted to a logarithm scale. It is interesting to 
note that the characteristics of this microphone are better than shown 
in the previous diagram, in that they do not discriminate as much 
against the low or certain high frequencies. 

Given means for faithfully recording sound and means for faith- 
ful reproduction of sound and means for the faithful recording and 


Transactions of S.M.P.E., August 1927 

reproduction of scenes, we have only the matter of proper time 
relation to effect faithful simultaneous reproduction of sound and 
scene which constitutes sound motion pictures. 

In the description which will follow, you will see how simply 
this has been accomplished in Vitaphone productions. As previously 
stated where the sounds to be recorded are sounds which naturally 

Fig. 7. Characteristics of a condenser transmitter. 

accompany the scene, they are preferably recorded in synchronism 
with the taking of the motion picture. This requires that the sound 
recording equipment and the camera must be driven at speeds which 
bear a fixed ratio to each other. Practically this is accomplished by 
driving both equipments from a single prime mover. In order to 
provide the necessary flexibility as regards locations of camera and 

Fig. 8. Carbon button type of transmitter. 

recording equipment, and also to permit the use of several cameras, 
with one sound recording equipment, it has been necessary to develop 
a synchronous electrical drive which is analogous to mechanical gears 
or shafting. This method applies if the sound is being recorded either 
with the taking of a picture or its reproduction. 

The Vitaphone — Rainey 303 

In reproducing the sound and scene records, it is only necessary 
that the two records be started at the correct points and run at the 
same speeds at which the records were respectively taken. In re- 
production it is entirely practical to provide mechanical couphng 
to maintain the proper speed ratio and there is, therefore, no need 
to use synchronous electrical drive used in connection with recording. 



Fig. 9. Electrostatic type of transmitter. 

Fig. 8 shows the construction of the familiar carbon button type 
of transmitter used in Public Address systems and radio broadcasting 
studios. The transmitter is of the double button, push, pull, air- 
damped type with a stretched duralumin diaphragm. This instru- 
ment is very satisfactory for Public Address and broadcasting work 
and for certain types of recording work. However, all granular 
carbon type of transmitters generate certain minute currents, which, 
when amplified and reproduced by a loud speaker, are known as 
carbon noises. If these currents are small in comparison with the 
currents generated by the sound waves picked up by the microphone, 
they are not objectionable, however, if the sound currents generated 
by the microphone are of the same order of magnitude as these 
carbon noise currents, the result is objectionable. 

304 Transactions of S.M.P.E., August 1927 

Fig. 9 shows another form of pick-up equipment, a condenser 
microphone and ampHfier. The advantage of this transmitter over 
the one just described, is that it has no carbon and hence can generate 
no carbon noise currents; however, its efficiency in converting air 
vibrations into electrical energy is much lower than the carbon 
button transmitter just described, and it is necessary therefore to 
amplify its output to bring it up to the same level as the output of 
the carbon transmitter. As its name implies, this microphone or 
transmitter is an electro-static condenser, in which the capacity is 

-O-Aif _ 


4f J?ii£ii5"DSTJ 

LLC a* 


s'r'&'sT»%u"'^-'^ ~ "" 



D°j^i:&r ' 




Fig. 10. Wiring diagram of amplifiers of a recording outfit. 

varied by the vibration of its stretched diaphragm in response to 
air vibrations. The capacity of the condenser is so small, that it is 
necessary to mount its amplifier with exceedingly short electrical 
connections ; otherwise the electrostatic capacity of these connections 
would still further decrease the already low efficiency. For this 
reason the microphone is mounted directly on top of the amplifier. 
Fig. 10 shows a simplified wiring diagram of the amplifiers of a 
Public Address system, a recording outfit or a reproducing outfit. 
If the input is a microphone, and the output feeds into loud speakers, 
we have a Public Address system. If the loud speakers are replaced 
by an electrical recorder, we have a recording outfit. If the micro- 
phone is replaced by a reproducer, and the amplifier feeds into loud 

The Vitaphone — Rainey 


speakers, we have a reproducing outfit. As previously mentioned, 
all of the units making up this amplifier are so designed as to maintain 
the general straight line characteristic which is essential to faithful 
recording and reproduction. This circuit shows a number of vacuum 
tubes connected with transformers. 

Fig. 11 shows the amplifier of a Vitaphone 1-B theater equip- 
ment. In addition to the amplifiers, we have mounted on this frame- 
work other panels which are essential to the practical operation of 
the system. Fortunately, or unfortunately, the arrangement of the 
apparatus of these panels does not follow the arrangement of the 
schematic circuit described above. The 8-B amplifier, whose input 

Fig. 11. Amplifier of Vitaphone equipment. 

is the output of the Magnetic Reproducer, is mounted at the bottom 
of the right hand frame-work. This amplifier panel carries a grid 
battery box, jacks for measuring currents in the filament and plate 
circuits, a transmitter cut-off key which is used in Public Address 
work for switching a microphone on or off, and in sound motion 
pictures is used for cutting off the magnetic reproducer. This panel 
also carried a potentiometer which makes it possible to vary the 
amount of amplification, and thus control the volume of the output. 
The transformers are mounted on the back of the panel. Above the 
8-B amplifier is a Volume Indicator panel, which is not now being 
supplied as a part of the theater equipment. The function of this 
panel is to give a visual indication of the output of the amplifier as 
a guide to the operator controlling the volume. Experience to date 
indicates that this is not absolutely necessary, if the records have 
been properly recorded. It is standard practice to have an observer 
located in the audience with a telephone to advise the operator 


Transactions of S.M.P.E., August 1927 

whether the volume should be raised or lowered in order to produce 
the most desirable effect for the audience. 

Above the Volume Indicator panel is the meter panel. These 
meters provide means for the operator to observe the current and 
voltage in various parts of the equipment. Above the meter panel 
is the microphone control panel which is not required in sound motion 
picture projection, but is used in connection with microphones for 
Public Address and recording work. This panel provides means for 
fading out one microphone and fading in another. At the top of 
the right hand frame-work is a volume control panel equipped with 

Fig. 12. A magnetic recorder. 

apparatus for controlling the volume of a number of loud speakers. 
The potentiometer on the 8-B amplifier just described, makes it 
possible to vary the volume of all the loud speakers up or down, 
whereas, the Volume Control panel makes it possible to vary the 
volume of the individual loud speaker or groups of loud speakers. 
At the top of the left hand frame-work is the power amplifier. 
This mounts four 50 watt tubes, and carries its own grid battery 
box, voltmeter and DC milliameter. 

The VitapJione — Rainey 


Fig. 13. A magnetic recorder. 

Below the 10-A amplifier is the 6000-A rectifier, consisting of 
three units. The lower unit carries a rheostat for controlling the 
filament current of the large tubes. Above that is the unit which 

Fig. 14. View of Vitaphone recording room. 

mounts two large rectifier tubes for rectifying 110 volt or 220 volt AC 
to give the necessary plate voltages for the 8-B and 10-A amplifiers 
previously described. 

Above this rectifier unit is the potentiometer filter unit. The 
filters are necessary to smooth out the rectified plate voltage so as 


Transactions of S.M.P.E., August 1927 

to eliminate objectionable hum, the potentiometer makes it possible 
to control the gain of the 10- A power amplifier at the top of the 
frame-work. The tubes used with the 10-A amplifiers require 750 
volts DC, which is dangerous, hence the high voltage wiring is all 
protected to guard against accidental contact. Safety switches are 
provided so that the power is automatically cut off in case the 
apparatus is opened. 


Fig. 15. Close-up of recording turn table. 

Fig. 12 shows a line cut of the magnetic recorder. This is of 
the balanced armature type, and the method of pivoting the armature 
and the means by which the armature controls the stylus are shown. 
There is also shown here a mechanical filter, which has the property 
of suppressing certain frequencies. This is necessary in order to 
maintain a proper straight line characteristic which has already been 
discussed. This functions with physical vibrations in the same 
manner as electrical filters with alternating currents of various fre- 
quencies. The field is excited by an electro-magnet. 

The Vitaphone — Rainey 


Fig. 13 shows what might be called a worm's eye view of a 
magnetic recorder, since the picture was taken from beneath to one 
side. The stylus is shown projecting at the bottom, and the energizing 
coil is shown on top to the left. 

Fig. 14 is furnished through the courtesy of the Vitaphone 
Corporation, and shows a view in a recording room in one of their 

Fig. 16. Scene in studio using electrical method of recording. 

studios. In the rear will be noticed two turn-tables on which the 
records are made. The panels to the right of the recorders mount 
amplifiers, switching panels and other control equipment. 

Fig. 15 shows a close-up of the recording turn-table with wax 
in place during the operation of recording. An attendant is shown 
viewing the record-cut through a microscope. This is deemed ad- 
visable to insure that proper recording is being effected, and that the 
stylus is making sufficient, but not too great an excursion so as to 
cut over into the adjacent groove. 

Fig. 16 is furnished through the courtesy of the Victor Talking 
Machine Company, and shows a scene in one of their studios using 
the electrical method of recording described above. 


Transactions of S.M.P.E., August 1927 

Fig. 17 is also furnished through the courtesy of the Victor 
Talking INIachine Company. It shows a typical scene in one of their 
studios using the now discarded acoustic method of recording. 

Fig. 17. Scene in studio using now discarded acoustic method of recording. 

Fig. 18. Comparison of frequenc}^ characteristics of electrically and acoustically 

recorded records. 

Fig. 18 shows the frequency characteristics of the output of new 
style phonographs with electrically recorded records and old style 

The Vitaphone — Rainey 


phonographs using old acoustically recorded records. It should be 
noted that the improvement in the new equipments is due to adding 
a band of low frequencies and cutting off a peak in the higher fre- 

Fig. 19 shows one of the balanced armature type of loud speakers 
used extensively in connection with Public Address systems. The 
construction is similar to that used in Radio Loud Speakers manu- 
factured by the Western Electric Company. The diaphragm is of 

Fig. 19. Balanced armature type of loud speaker. 

duralumin, the center of which is connected to one end of the balanced 
armature. This balanced armature construction is used in the 
recorder and reproducer as well as in this form of loud speaker. 
In the reproducer the movement of the armature by the needle 
following the groove in the record generates sound currents which are 
amplified and then connected into sound by the loud speakers. 

Fig. 20 shows one of the Western Electric Company's newer 
types of loud speakers, and the one now used in Vitaphone installa- 
tions. It is electro-magnetic, and requires an outside source of direct 
current for excitation. It is of the mo\dng coil type, and has a 
stretched duralumin diaphragm. The efficiency of this loud speaker 
is considered higher than the one previously shown. Its character- 
istics approach more nearly a straight line. 

Fig. 21 shows one of the horns used with the 555-W loud speakers 
in connection with Vitaphone installations, and is designed to give 
maximum efficiency with minimum distortion. Notwithstanding its 


Transactions of S.M.P.E., August 1927 

appearance, it is actually designed to give a straight line character- 

Fig. 22 shows diagramatically a side elevation of a Vitaphone 
installation. This shows the installation of the amplifier equipment 
in the projector room with leads running to the loud speakers, one 

Fig. 20. Electro-magnetic type of loud speaker. 

above and behind the screen, and one below immediately in front 
of the screen. Proper location and the number of loud speakers for 
a given installation depends on the size and acoustic properties of 
the theater. 

Fig. 23 shows the Vitaphone equipment installed in connection 
with a Simplex projector. The motor I used for driving the projector 
and the turn-table is designed to operate on 110 volts DC or AC 
commercial service, and is provided with a special circuit by means 

The Vitaphone — Rainey 313 

of which the speed of the machine is maintained at 1200 RPM. 
It is mounted on a substantial base 1-a, supported by three telescop- 
ing legs by means of which its height may be adjusted. The control 
circuit is contained in a steel box ^, and is connected to the motor 
by a multi-conductor cable encased in flexible conduit. A special 
1/5 H.P. shunt or repulsion type motor is furnished together with 
its control circuit, according to whether the power supply is a nominal 
110 volts DC or AC. 

FIg. 21. Amplifying horn. 

This equipment 3 consists of a drive or gear box 3-a mounted 
on the same base as the motor and coupled directly to the shaft of 
the motor, a vertical extensible shaft 3-b equipped with universal 
joints and a second drive 3-c which is a bevel gear box and replaces 
the speed regulator of the projector machine. By means of these 
two sets of gears the speed is reduced from a motor speed of 1200 
RPM to a speed on the projection machine shaft of 90 RPM, which 
corresponds to a film speed of 90 ft. per minute. 

On the opposite end of the motor from the projector driving 
mechanism is the turn-table equipment, 4- The turn-table mechan- 
ism is mounted on a heavy telescoping pedestal base 4-«, the three 
supporting legs of which are provided with adjusting screws so that 


Transactions of S.M.P.E., August 1927 

it may be leveled. A worm gear mechanism is housed in a casting 
in the top of the pedestal. The shaft of the worm projects outward, 
and is connected to the driving motor shaft through a flexible coupling 
4-6, designed to prevent the transmission of vibrations from the 
motor to the turn-table. The gear wheel which meshes with the worm 
carries a vertical shaft on which the turn-table disc is mounted. 
Between the gear wheel and the vertical shaft of the turn-table is a 
mechanical filter or "shock-absorber" consisting of light springs 




Fig. 22. Side elevation of Vitaphone installation, 

designed to prevent the transmission of gear noises from the worm 
gear to the turn-table and thence to the record and reproducer. 
The worm gear ratio is such as to reduce the speed from 1200 RPM 
to 33 J RPM, which is the correct turn-table speed. 

The turn-table is designed to accommodate 18 inch records, and 
has a clamping device 4-c to hold the record firmly against its surface. 
A guard 4-d is provided to protect the rotating parts. 

The operation of Vitaphone equipment naturally divides itself 
into two parts, (1) recording, and (2) reproducing. Briefly, the 
operation of recording equipment is as follows : 

First, the set is prepared to meet all of the requirements for 
ordinary motion pictures in the usual manner. This, of course, must 
be done in a studio which is acoustically suitable, i.e., free from 
extraneous noise during the recording, and not subject to objection- 
able reverberations or echoes. The microphones are placed so as to 
pick up in proper volume the sounds which it is desired to record. 


The Viiaphone — Rainey 


The film in the camera behind the shutter is marked, the recording 
wax is placed on the turn-table and the inter-locking electrical drive 
which maintains synchronism between the camera and the recorder 
is energized. 

The recorder is lowered onto the wax disc and the motor started, 
and the act produced. The sound recording is effected from the center 
of the disc to the periphery instead of the reverse as in the case of 
commercial phonograph records. In order to insure proper amplitude, 
and to insure high quality, the recording is observed under a micro- 
scope during the process. The beginning of the cut on the inside of 
the record is marked b}^ an arrow which will indicate the starting 
point of the record for reproduction. From here on the preparation 
of sound and film records for production follows standard procedures 
in phonograph and moving picture practice. 


(3-A)jSEAa_ 30X 



a- con-tsol. SOX 

Fig, 23. Showing turn-table for record connected up with projector. 

In reproduction the film is placed in the machine, the starting 
frame on the film which is marked "START" with the designating 
number of the film, is placed exactly in the center of the aperture of 
the motion picture machine when the shutter is in the open position. 
The corresponding sound record is placed on the turn-table with 

316 Transactions of S.M.P.E., August 1927 

the needle of the reproducer opposite the arrow on the inside groove. 
With the film and record thus set, the amplifiers should now be 
turned on, the potentiometer set to give the desired volume, pro- 
jector light turned on and the starting switch on the control box 
operated. This starts both records simultaneously and the show is 

Reference has been made to a photographic method of recording 
sound in contrast to that which has just been described. The Western 
Electric Company is now engaged in equipping the projector used 
by the Vitaphone Corporation so that it will accommodate "Movie 
Tone" film. This film carries the sound record photographed on its 
margin. "Movie Tone" is a trade name for sound motion pictures 
now being made by the Fox-Case Corporation, but not yet released 
to the public. It is contemplated, therefore, that future projectors 
will be provided with means for reproducing disc and photographic 
records in proper time relation with the picture. This will make it 
possible for any theater to reproduce Vitaphone productions and 
"Movie Tone" films. The Western Electric amplifiers and loud 
speakers will serve in either case. 

"Movie Tone" differs considerably from the Vitaphone process. 
The camera which records the movements of the performers on the 
film is provided with means for varying the intensity of Hght falling 
on the margin of the film. The sound vibrations from the performers 
actuate a microphone, the same as that described for the Vitaphone. 
The output of the recording amphfiers, however, instead of actuating 
a stylus cause variations in the intensity of light falling on the margin 
of the film. 

The presentation of a "Movie Tone" production is a reversal of 
the process just described. A standard film carries both picture and 
sound record, which is run through a motion picture projector to 
which has been attached a reproducing unit. This unit includes a 
light which is focused by a lens system through a narrow slit onto 
the sound record of the film. As the sound record on the film passes 
the slit it interrupts the constant light shining through it, setting 
up light variations corresponding to those photographed. The light 
falls on a photo-electric cell, which has the property of converting 
variations in light into electrical currents. These electrical currents 
are then amplified in the manner already described in connection 
with Vitaphone equipment. 

The Vitaphone — Rainey 317 


Me. Richakdson: I would like to ask Mr. Rainey a few ques- 
tions. First, with regard to the impression of the photographic record 
of sound on the film itself, is it not the fact that since the light 
source by which it is projected is itself stationary, any movement in 
the nature of a displacement of a film frame over the projector aper- 
ture would distort the sound? Second, is it not a fact that even the 
smallest possible amount of oil upon the sound record on the film 
would greatly impair or entirely ruin the sound effect of the portion 
upon which the oil lay? Third, is it not a fact that any shrinkage or 
stretching of the film stock, or the straining of the sprocket holes, 
or their abrasion through wear would affect the sound reproduction? 

Mr. Rainey: I think I know what is running through Mr. 
Richardson's mind. I have heard demonstrations of film productions 
just as convincing in quality as that which you have just heard. 
The merits and demerits of one or the other of the two methods of 
recording and reproducing would form the basis for a long discussion, 
and I think it would be premature to start such a discussion at this 
time. The effect of oil and dirt on reproduction are practical prob- 
lems which must be dealt with, and which do not appear unsur- 

Mr. Hill: I should like to ask if the piano reproduction was a 
straight line reproduction from 16 to 5,000. 

Mr. Rainey: Approximately yes. I was trying to get this idea 
home when I called that jagged line a straight line characteristic 
because the human ear cannot always recognize deviations from a 
straight line characteristic. The reproduction to which you have 
just listened was good. Its characteristics are probably as near a 
straight line as some of the straight line characteristic curves which 
were shown on the slides. The output of the horns you heard had 
a very good straight line characteristic, and yet the production which 
you heard in the particular place where you were sitting may not 
have been as good due to the peculiar accoustics of the room and the 
particular place in the room where you were listening. The other 
end of the room behind the horns might easily produce a detrimental 


Merrill J. Dorcas* 

IN SUPPLYING artificial illumination for a motion picture 
studio the primary consideration is to secure the quantity and 
quality of light that will have the desired effect on the film. This 
subject has been dealt with in many papers and discussions. In the 
present paper the effect of the light on the actors rather than the 
film will be considered. I wish to call your attention to two of the 
many known physiological effects of light on human beings. Many 
physicians have become interested in these physiological effects in 
the last five years. Their research work has enabled us to form certain 
definite ideas that might be important in some applications of light 
in studios. 

One of the earliest noticed physiological effects of light in studio 
practice was the irritation caused by the ultra-violet light from arc 
lights. This irritation was particularly noticeable in the cases where 
conjunctivitis or "Klieg eye" resulted. This was annoying, possibly 
dangerous, and resulted frequently in lost time by high salaried 
employees. Klieg eye has now disappeared in most studios where 
glass screens are used. Consideration of the phenomena involved 
from a theoretical viewpoint indicates that this method is sufficient 
for complete protection and is probably the best possible method of 
preventing irritation of the eye. The theory is, briefly this: Light of 
the shorter wave-lengths which causes eye burn has no effect on the 
film. Ordinary glass transmits practically all the photographically 
active light and none of the injurious light. This statement is not 
absolutely exact but the variations from it are minute. Ordinary 
glass transmits light of wave-lengths longer than about 3400 AU. 
It absorbs light of wave-lengths shorter than this. Light of wave- 
lengths shorter than 3400 is very weak in its photographic effect 
though it is possible to photograph such light, if sufficiently intense, 
down to wave-lengths as short as 2400 AU, if no lenses are used. 
Ordinary photographic lenses, however, are made of glass and there- 
fore in any case will transmit to the film only that quality of light 
which the glass screen is capable of transmitting. Furthermore the 
reflecting power of common substances for these short waves, or, 

* Research and Development Laboratories, National Carbon Company, 
Inc. Cleveland, Ohio. 


Effects of Light— Dorcas 319 

as we might think of them, these colors of ultra-violet, is so different 
from that of visible light that if it were possible to make use of them 
by inserting quartz lenses in the camera very unnatural tones would 
result. For example, human skin absorbs rather than reflects light 
of wave-lengths shorter than 3200 AU and would therefore appear 
black if photographed with only short wave light. It is therefore 
advantageous to filter out this light if panchromatic films are to be 
used and if little or no make up is to be required of the actors. Light 
of wave-lengths longer than 3400 is reflected by most substances in 
a manner similar to visible light and we can therefore profitably use 
all the light that will go through ordinary glass. 

Any glass will reflect about 8 per cent of light of all wave- 
lengths and colors from its two surfaces. The glass screen there- 
fore diminishes the total intensity of illumination by this amount. 
This is scarcely noticeable photographically. The slight loss in 
intensity is balanced by the advantage of the slight diffusion possible 
with the glass screen. To briefly sum up this phase of the discussion, 
the irritation to skin and eyes is caused by light from 2700 to 3200 AU. 
It can be filtered out by ordinary glass, which is as opaque to this 
range of ultra-violet as a sheet of steel. By filtering it out we lose 
but a small percentage of photographic power due to reflection losses 
from the glass screen. Therefore glass screens in practice will satis- 
factorily prevent Klieg eyes and there is no theoretical reason to 
think that this method can be improved upon. 

Light of various wave-lengths has many other complex physio- 
logical results which are just beginning to attract serious attention 
and general clinical study. One well known physiological action is 
the effect of excessive infra-red or heat rays in producing sunstroke 
effects. Thus far in studio practice the intensities of illumination 
employed have probably not been sufficiently high or of sufficiently 
long duration to make such effects possible. They may, however, 
prove to be a hmiting factor in the quality and intensity of illumina- 
tion which can ultimately be used with safety in studio lighting. The 
sjTiiptoms following excessive exposure to near infra-red energy, 
which always accompanies visible light while commonly known as 
sunstroke, is in reality a heat stroke. It is due to the great penetrat- 
ing power which this kind of radiation has for the body tissues. 
It passes into the bod}^ for a considerable distance before being ab- 
sorbed as heat. This light is technically described as radiation of 
wave-lengths of about 6500 to 42000 AU. If of sufficient intensity 


Transactions of S.M.P.E., August 1927 

the effects may be many and profound. One of the most serious is 
irritation of the membranes covering the brain and spinal cord; in 
other words, a form of meningitis. In the tropics exposures of the 
unprotected body for 5 minutes to direct sunhght has been reported 
as fatal. Protection is secured only by pith or cork helmets and spine 
pads. The fact that in the temperate zones sunstroke is rare and in 
the tropics great precautions are necessary gives us a measure of the 
intensity limits of this radiation which is safe for human beings. 



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^U. . 





• / \ \ 


300 '^ao 300 c»oo 7ap 3oo /7ju<. 

/'e.on US Buesfiu OF 3T»none.DS t>c>£r,T,ric f=^fsc S3S 

Fig. 1. The Spectral Regions Transmitted and Absorbed 
by the various screens. 

Modern studios already are using intensities of visible light which 
approach that of noon summer sunlight in temperate latitudes. 
Scientists have determined the amount of penetrating radiation or 
heat content of such sunlight. This quantity of heat radiation there- 
fore approaches the known limits which the human body can endure 
with comparative safety. Recently quantitative measurements 
of the comparative light and heat content of the radiation from differ- 
ent types of light-sources have become available. From the point of 
view just discussed, let us examine the various important artificial 
light-sources for the relation between the amounts of visible light, 
namely the radiation between 3700 to 6500 AU with the corresponding 
amounts of heat or infra-red radiation, that is, the amounts between 
6500 to 42000 AU. 

These figures are from some work recently done at the Bureau 
of Standards by Coblentz et al and reported in Scientific Paper 539. 

Effects of Light — Dorcas 321 

The figures were obtained by means of a thermopile and the follow- 
ing screens. 

Spectral Component Radiation in Per Cent of the Total to 120,000 A U, 
1700 3200 3700 4800 6500 14000 42000 
to to to to to to to 

Source 3200 3700 4800 6500 14000 42000 120000 



June 28, 1926 

llA.M 1.8 3.2 13.3 22.0 39.5 19.7 0.5 

122 Ampere 

High Intensity 1.2 2.5 11.6 14.2 29.2 27.8 13.5 

29 Ampere 


WhiteFlame 2.3 1.7 8.6 8.4 21.0 33.0 25.0 

Neutral Core Negative 

Solid Positive 21 Amp. 0.9 1.2 1.9 2.9 20.7 56.7 15.6 
1500 Watt 

Type C incandescent 0.0 0.2 1.0 3.8 29.8 54.2 11.0 
From Bureau of Standards Scientij&c Paper 539. 

The studio problem is to secure a light which is photographically 
active and approaches the intensity of sunlight. The heat rays which 
are physiologically dangerous when present in excessive amounts 
should not greatly exceed the quantities found in sunlight in the tem- 
perate zones. It will be seen from the tables that noon June sunlight is 
approximately 35 per cent Hght and 60 per cent heat using these 
terms in the above defined sense. The hght from a high intensity 
arc lamp using 125 amperes is similar in its composition, that is 26 
per cent light and 57 per cent heat. If transmitted through a glass 
screen the ratio would be very nearly the same because ordinary 
glass transmits energy of all wave-lengths from 3400 to 45000 ap- 
proximately, except the 8 per cent that is reflected. This reflection 
is about the same for all wave-lengths, therefore the ratios of light 
to heat, when we define them as we have in this paper, are unchanged. 
The ratio of Hght to heat for a source such as the high intensity arc 


Transactions of S.M.P.E., August 1927 

lamp, being similar to sunlight, it can be emplo3^ed in intensities 
which give the similar visual and photographic effects with no 
greater hazard from the heat rays than is common to June noon day 

PRncneoriffTic Film 

/nc/^ri OE5 c £n r 
Typ£ c 


\pe>^r-i&^Y£LL.Oh/\ (^^££n I 3i.c/£: \ j^/ocst 

70i^£:> /=f'<^ 




Fig. 2. Photographic effect of different light sources with ISToyiol Filter 
and Eastman Commercial Panchromatic Film. 

The low intensity flame arcs show a slightly less favorable 
distribution of radiant energy, the exact quahty of the radiation 
varying with the lamp design and conditions of operation and with 
the type of carbons employed. A typical case is the 30 ampere 
white flame arc with reflector which on direct current shows 17 per 
cent of photographically useful Hght to 54 per cent of heat radiation. 
As in the previously described case of a high intensity lamp, the use 
of a glass screen does not sensibly change this ratio. In this case for 
a visible illumination equivalent to sunlight the heat radiation would 
be nearly twice as great as that normal to temperate latitudes. 
' Next we come to the so-called neutral carbon arcs in which the 
principal source of radiation is the incandescent carbon craters, 

Effects of Light — Dorcas 323 

and our table, for example, shows that a neutral cored carbon arc 
trim on a small current of 20 amperes gives 4.8 per cent Hght and 77 
per cent heat. A similar situation is also found with the incandescent 
tungsten lamp. With the same instruments and method of measuring, 
a 1500 watt gas-filled "C" type tungsten incandescent bulb, operat- 
ing at its rated voltage, will give about 4.8 per cent of light and 
84 per cent heat, a ratio seven times as high as that of the high in- 
tensity arc, and nine times as high as is found in sunhght. This 
suggests, therefore, that if visible Hght approaching sunlight were 
to be supphed by incandescent sources of these types, the quantities 
of near infra-red energy might reach such values that human beings 
could not safely work in them for any but very short periods. It is at 
least safe to conclude that where intense illumination is required, the 
employment of incandescent sources containing a high percentage of 
infra-red would introduce certain new problems and hazards re- 
quiring careful clinical attention and investigation. By phj^sical 
methods it may be possible to overcome a portion of these difficulties. 
We have seen that the undesirable ultra-violet can be filtered out of 
the radiation by glass screens. Some infra-red can also be removed in 
a similar manner. Our table shows that the particular portion of 
the infra-red spectrum that we are considering can be divided into 
two parts by means of a water-cell or screen, which consists in this 
case of a layer of water 1 centimeter thick. Such a screen absorbs 
the very long wave-lengths below 42000 AU and thereby removes 
about 33 per cent of the total heat from sunlight. For the artificial 
sources considered, the absorption of heat rays is as follows: 49 per 
cent of the heat rays from the high intensity arc, 61 per cent from the 
30 ampere white flame, 73 per cent from the neutral core spotUght, 
and 65 per cent from the incandescent bulb. 

Immersing an incandescent bulb in a water bath or allowing 
water to flow over the bulb or over a glass screen in front of the 
bulb would therefore remove considerable percentages of the infra-red 
energy. -The portion of the infra-red absorbed by water is physiologic- 
ally speaking the least dangerous however, since the human tissues 
are themselves chiefly water and therefore these rays have compara- 
tively low penetrating power. Because they are absorbed near the 
surface of the body they give the strongest effect of sensible heat to 
the skin and therefore a warning of their presence in undue excess. 
Therefore the water screen would serve only to remove the energy of 
low penetrating power, but would not diminish the near infra-red 

324 Transactions of S.M.P.E., August 1927 

radiation which can penetrate deeply. It is possible, however, that 
suitable glass screens could be devised which would filter out a portion 
of this near infra-red without absorbing too much of the visible light. 

Recently it has become possible to duplicate the color ranges 
of the incandescent bulb by the light generated in the high intensity 
arcs while still retaining the high photographic efiiciency and com- 
parative coolness of this type of radiation. The accompanying chart 
shows the photographic effect on Eastman commercial panchromatic 
film of light from a new carbon electrode and an incandescent bulb. 
It is seen that the relative effect of the reds and yellows compared to 
the blues and violets is about the same in each case. 

For the present, therefore, in so far as it may be necessary to 
employ intensities of illumination approaching or exceeding sunlight 
in studio work it would appear that the high intensity carbon arcs 
modified in color if necessary for panchromatic films, constitute the 
safest known source of light now available with the exception of the 


Two physiological effects of the radiation from artificial and 
natural light-sources are discussed, one arising from the ultra- 
violet, the other from the infra-red regions of the spectra. Klieg 
eye, once a serious problem for the actors, has been satisfactorily 
solved in most studios by the use of glass screens. This protects the 
actors from the chemically active shorter wave-lengths, which 
never reach the photographic film in any case because excluded by 
the camera lenses. The method involves only a slight loss in desirable 
radiation through reflection losses from the screens employed. 

A less well-known hazard is the possibility of heat stroke effects 
in the presence of sufficiently high concentrations of the extremely 
penetrating infra-red rays. With the tendency toward concentrations 
of artificial light in studio work approaching sunlight in intensity 
recent measurements have shown that certain incandescent sources 
will contain infra-red radiation in amounts that are far from negligible 
the possible hazards of which require careful investigation. In this re- 
spect it appears, (a) that incandescent sources such as the solid carbon 
or neutral cored arcs, and the filament lamps constitute a class of 
artificial illuminants which have the smallest factor of safety; (b) that 
the low intensity flame carbons occupy an intermediate and fairly 
favorable position; and, (c) that the high intensity arcs closely 

Effects of Light — Dorms 325 

approaching sunlight in radiation quahty constitute from the physio- 
logical standpoint the most desirable form of artificial illumination, 
where concentrations of Ught of the order of noonday sunlight are 


Mr. L. a. Joxes: I should Hke to point out, in connection Tvith 
the author's statement relative to the spectral distribution of sensi- 
tivity of photographic materials, that they are in fact veiy sensitive 
in the short-wave-length region. It is customary to define sensiti\dty 
in terms of energy per unit area since in dealing ^ith ultra-vdolet 
radiation it is impossible to specify sensiti^-ity in terms of A^isual units. 
Defined in this manner sensitivity is practically constant in the 
region between 250 and 350 m^. For radiation of wave-length 
shorter than 250 m/i the sensitivity decreases gradually while for 
radiation longer than 350 m^ it decreases rather rapidly becoming 
practically zero at 550 m^u for ordinary blue sensitive plates and films. 

I believe the author's discussion of the problem unplies that all 
radiation of wave-length longer than 340 m/i is useful for the re- 
production of the visual impressions. The maximum of visibility 
for the himian eye is at 550 m^t, decreasing rapidly for shorter and 
longer wave-lengths. Assuming the sensitivity at the maximum to be 
represented by 100 per cent, the sensitivity at 400 m^ is only one- 
tenth of 1 per cent. It is evident that the use of radiation of wave- 
length 400 or shorter can only produce very marked distortion of 
the brightness scale in colored objects. If it is desired to obtain an 
approximately correct reproduction of the brightness factors all 
radiation of wave-length less than 430 should be absorbed. 

^Ir. Buttolph: ^lay we have that first chart showing the 
energy distribution of various sources? In the original paper from the 
Bureau of Standards, by Coblentz, Dorcas and Hughes, this data 
was also given for a quartz mercurv^ arc and the relative energy dis- 
tribution of this arc dift^rs so slightly, so far as the division between 
the visible and infra red is concerned, by so slight an amount that 
I believe this chart would be highly illuminating if the data for the 
quartz mercurv' arc were added. Is it possible to hav^e that done? 
As given in this table, reading from left to right, the percentages are 
5.7 for 170-290, 2.8 for 290-350, 2.5 for 350-450, 6.7 for 450 to 600, 
3.2 plus 20.5 plus 58.6 for 600 to 12,000. Adding these last three 
figures, as was done here, for comparison between the infra red and 

326 Transactions of S.M.P.E., August 1927 

visible you have approximately a total of 82 as against 60 for sunlight 
and 95 for the gas-filled tungsten lamp. This energy distribution 
and the further localization of the visible in a few lines at the maxi- 
mum of visibility is the explanation of the claim often made that for 
a given intensity, either visual or photographic, by mercury vapor 
lighting you have a relatively small amount of total energy entering 
the eye or camera as the case may be. 

Mr. Burnap: I should like to ask Mr. Dorcas if he knows 
at what efficiency the 1500-watt incandescent lamp was operated 
in making these comparisons. 

Mr. Dorcas: I don't know the lumens per watt; it was labeled 
115 volts and ran at this controlled with a voltmeter. 

Dr. Gage: It has been questioned in the literature whether 
infra-red might be harmful, and I think we have here an indication 
in tropical countries of heat stroke due to penetrating radiation. I 
should like to inquire — perhaps some of the cinematographers with 
experience in the tropics could help us in this — as to whether the 
heat stroke does not also require that the temperature of the air be 
high ; that is, if the body cannot take care of a considerable amount 
of red radiation if the body is kept cool by the air? That factor would 
certainly have a considerable interest in operating in the summer 
when the air temperature of the studio gets hot. 

Mr. Gregory: I have had several experiences to make me 
believe that the surrounding air temperature does not have any great 
effect. I have seen sun stroke among snow shovelers on the mountain 
top where the temperature was low but the sunlight intensity very 
high and have worked near the equator with blondes, who were made 
sick for days whereas those protected by the pigmentation of the 
skin were unaffected. 

A Member: As the previous speaker pointed out, infra-red 
penetrates and appears in the body well below the surface, and the 
physiological difficulty is to get that heat out. It can be demonstrated 
in the laboratory that the blood temperature of the body can be 
raised by radiant heat corresponding to blood elevations in cases of 
fever, which cannot be done by hot air or a hot bath. 

Mr. Jenkins : A multiplicity of copper screens spaced apart will 
take out heat much faster than it takes out Hght, and that was 
strengthened in my mind by the fact that chains are hung before 
large furnaces to keep the heat from the men, and this led to the 
testing of copper screens spaced apart in order to get a greater sub- 

Effects of Light— Dorcas 327 

traction of heat than of Hght in an arc lamp, which was the source 

Mr. Mayer: Apropos of Mr. Jenkin's comment, I experienced 
the same condition. We use a 500- watt over-voltaged lamp which 
must be over-voltaged, and after a lot of experimenting a fine mesh 
screen of copper made a cooler beam on the subject and diffused the 
light satisfactorily. 

At a recent meeting of the Societe Frangaise de Physique M. 
Chretien showed the Hypergonar, a supplementary afocal system, 
composed of cylindrical lenses, which can be used for compressing 
the horizontal scale of a motion picture to half normal, while retaining 
the vertical scale, thus enabling twice the field to be recorded. The 
picture thus deformed is restored to its normal dimensions by placing 
the same system in front of the projection objective. M. Kitroser 
showed the Polytypar consisting of a semi-transparent platinized 
mirror, that can be placed in front of the camera lens so as to reflect 
the image of a miniature scene or model, while the actors or the like 
may be taken direct. The image of the model is located at any con- 
venient distance by an achromatic and aplanatic coUimating lens. 
Masks may be used to block out such parts as desired. This has been 
successfully used in a picture not yet released. (Sci. Ind. Phot. 
1927, 7A, 64.) 


E. J. Wall 

SOME attempt has been made to collect a few patents relating to 
this subject, mainly it must be confessed from English sources. 
To make a complete list of the patents of all countries would need 
rather more time than I have had a chance to give to it. 

Clive, J. C. E. P. 2, 139-1855. A portrait or group is taken on glass and the 
background removed. A scene to form the background is then taken on the 
other side of the glass or on a separate sheet, which is placed behind the first. 
Figures or objects taken at different times can be brought into one picture. 

Laroche, W. S. — E. P. 820-1866. Placing in front of and close to sitters a screen 
or frame covered with canvas with an opening cut in the latter. The opening 
may be surrounded with ornamentation. By means of the ordinary camera 
and processes, the frame and sitters are photographed at the same time, the 
result being a composite picture with portrait and ornamental frame com- 

Hemery, T. G. — E. P. 89-1870. Various methods of obtaining impressions of 
two sitters on one plate are detailed, but one that may be of interest is as 
follows: one of two similar impressions of one figure is rendered opaque and 
is placed in front of a second plate in the camera so as to print a transparent 
figure thereon. The second plate and the unused impression of the first 
figure are combined to afford a single negative. According to another method 
the background in one negative is transparent, and opaque in the other and 
the two are superposed and a transparency made of the combination. 

In 1875 an EngUsh provincial photographer, named Tilley/ 
advertised that he had a new invention of photographic combinations 
and that while practically defying one and all to discover his method, 
announced his intention of giving his system free of charge to anyone 
who discovered his secret within six months. Soon after J. Werge,^ 
a well known figure of the early days, described a method of putting 
in a background by photographing a sitter against a dark plain ground 
and using another and paper negative of the desired background from 
which the figure was cut and superposing on the original negative for 
printing. Twelve months later Tilley's secret was out, for the patent 
was published^ and it resolved itself into photographing a sitter first 
against a dark background, then photographing the desired ground 
on the same plate by the interposition of a positive just in front of 
the plate, the sitter still retaining his pose, and being thrown into 
comparative darkness by curtains. 


Trick Photography Patents — Wall 329 

E. Dunmore^ described the use of separately taken landscapes 
or interiors for this work, as employed by a Mr. Edge. The latter in 
describing his work^ said: "The carte-de-visite photograms of figures 
with natural backgrounds, made by me some 20 years ago, were 
printed from two different negatives ; the figure and foreground from 
one, and the natural background from the other." Some excellent 
pictures are reproduced. Practically the same method was patented 
by L. Schulze.^ 

In 1894 F. F. Weeks and J. Riley^ patented a method of posing 
a hving or artificial model in front of a plain white background. The 
negative was then blocked out, leaving nothing but the subject 
visible. An enlargement was made and scenic effects, etc., were 
hand-drawn on that. This print was then photographed to make the 
"working negative." The patent is very comprehensive and worth 
careful perusal. 

There seems to be a curious gap here, for the next patent that 
is of any interest was granted to F. J. Dischner^ which is fully de- 
scribed and illustrated in the British Journal of Photography. This 
is again the use of black grounds and a transparency of the natural 
scene, etc., in contact with the plate while the sitter retains his pose 
against the white ground. This is essentially the older process 
without, so far as I can see, any point of novelty. A precisely similar 
patent was granted to F. J. Mohr and J. Vincent.^ 

The most important reference that I have been able to find is to 
"an apparatus for making composite negatives direct in the camera. 
Sold by Halford & Thompson, 4 Broadway, Hammersmith, London, 
W."^° This would seem to have been invented by W. B. Henderson^^ 
and is officially described as "a shutter or screen for exposing a plate 
in sections," and the specification itself does not give one any idea 
of the possibilities as outlined in the British Journal of Photography 
as follows: 

"The apparatus consists of a framework very similar to the skeleton of an 
Eastman roll-holder, which is mounted on a square frame by struts which allow 
its distance from the supporting frame to be adjusted. The frame fits into the 
back of the camera, and the roller mechanism is thus supported inside the camera 
at a distance of say, 3 inches to 4 inches from the focusing screen. It is, however, 
but the means of bringing into action the essential part of the apparatus — viz., a 
flexible band wholly of black paper with certain apertures in it, or partly of the 
paper and partly of celluloid, for the distinct purposes which will be seen in a 
moment. In either case the band is wound across the space between the two rol- 
lers, and is caused to halt at any desired point by register marks on its edges and 

330 Transactions of S.M.P.E., August 1927 

one center mark on the framework which supports it." The method of obtaining 
three images on the same plate are then given it being stated that they "merge 
into each other without the sign of a join, so that all three may be printed as a 
complete photograph, or each one completed separately." Then the method of 
securing a frame round a portrait is given. But the most interesting part is as 
follows : 

"It is, however, in the use of the apparatus for employing miniature accesso- 
ries as full sized backgrounds that the most ingenious apphcation of the apparatus 
is found. The manipulation is precisely the same as just outlined, that is to say, 
the sitter is photographed through a mask, any size and shape thought desirable, 
the complementary disc wound into place, and a second exposure made on the 
miniature model of a room, a doorway, a wall, or any other object thought 
suitable as a background or accessory. The blinds, both all-black and black 
and transparent are obtainable in considerable variety, devised to serve the 
photographer in the production of commercial styles of portrait. We have not 
spoken of the amateur model of the apparatus devised to fit on the lens hood, but 
it has certain valuable properties for landscape photography in the way of equal- 
izing exposures and even producing combination photographs in the field." 

This instrument was called the "Thaumatoscope" and was sold 
for 30 shilhngs ($7.50). It would seem to me to be a very distinct 
anticipation of many of the more recent devices used for cine work. 

We then come to the patents of H. Sontag,^^ of Erfurt, Germany. 
In these the background was projected on to a translucent or trans- 
parent screen behind the sitter. After detailing the defects of prior 
methods the specification reads: 

"The drawbacks in question are obviated by the new process which enables 
the object and the background projected to be photographed with only one ex- 
posure of the plate. The object can be Ughted both by daylight and by artificial 
light. The process itself by which this result is obtained, chiefly consists in the 
picture forming the background being projected on a screen colored wdth a 
color which has slight chemical action, such as yellow, red, green or the Hke, the 
object to be photographed, suitably lighted, being in front of the said screen, and 
being photographed with the background projected by a single exposure of the 

It is unnecessary to quote further; enough has been said to show 
the purpose of the invention. But a further reference-^ to this patent 
gives some added information. 

E. Neame (E.P. 153,111, 1919) 

Elaboration of the above method. 

So far all these patents relate to stills, not cin^ work. You may 
or may not consider them important, but the only excuse I make for 
abstracting them is that I consider that if a process has been applied 
to ordinary photography, there is absolutely no invention in applying 

Trick Photography Patents — Wall 331 

it to cinematography. If I am wrong, then we have a somewhat 
absurd position, that is best illustrated by a supposititious case. Thus, 
the intensification of the silver image with lead salts has been known 
since about 1876, yet so far as I know, has never been used for cine 
work, hence it can be patented as an invention when used in this 
way, although known for 56 years. 

The following patents are applicable essentially to cinema- 
tography : 

Patents relating to the making of Composite pictures. 

Dawley, J. S. (U. S. P. 1,278,117, 1918) Introducing backgrounds with a sheet 

of glass, acting as a light- splitting mirror through which the images of 

actors are transmitted direct, while the background is reflected. 
Brownley, L. E. (U. S. p. 1,355,648). Making stencils photographically from 

negatives and combining silhouette or detail figures with a background. 
Presicce, G. de L. (U. S. P. 1,358,110; E. P. 144,408, 1919. )Reflection of cin^ 

pictures by large mirror to camera, with actors between mirror and camera. 
Flo RES, U. (F. P. 511,168) Scenes and backgrounds projected on to suitably 

placed screens. 
Behrens, J. (D. R. P. 323,939) Background projected on to translucent screen, 

recalHng Son tag, etc. 
Petra Akt. Ges. (D. R. p. 326,527) Ditto. 
Hall, W. L. (U. S. P. 1,372,811) Miniature paintings placed in predetermined 

places and taking them with portions of scene not obscured by miniature. 
Smith, H. A. (U. S. P. 1,394,797) Projected images which may be of objects at 

different distances. 
GoETz, H. I. (E. P. 169,233) Making silhouettes, as outlined in some of the early 

still patents. For moving pictures, two negatives are simultaneously obtained, 

one through a filter of the same color as the background, the other with 

complementary-colored filter. 
RuTTMANN, W. (D. R. P. 338,744) Three transparencies between the camera 

and a Hght. One is fixed, the second adjustable in its own plane and the 

third adjustable to and from the camera. 
Barker, D. (E. P. 186, 189) Making masks and using them before a background. 
CoppiER, A. C. (E. P. 186,649) Method similar to Weeks & Riley, of 1894. 
Capellani, p. (F. p. 548,352) Mirror system for introducing pigmy images. 
MiCHELER, H. (D. R. P. 379,376) IncHned transparent mirror superposing a 

second scene on principal one. 
Douglass, L. F. (U. S. P. 1,438,906; 1,477,999; 1,504,328; 1,531,693; 1,532,236; 

1,591,296; 1,424,886; 1,482,068; 1,482,069; 1,482,070; 1,508,509; 1,543,065) 

All refer to lenses, or prisms to obtain two images on the one picture space. 
Griffith, D. W. (U. S. P. 1,476,885) An artificial scene built in miniature out- 
side a window, with actor in front of window. Separate lighting for actor 

and scene. 
Kessel, H. von (E. p. 219,993; D. R. P. 399,652) Practically making silhouettes 

by the use of two backgrounds and combining with the object negative; 

variant of the very early types. 

332 Transactions of S.M.P.E., August 1927 

Driger, J. (F. P. 579,605) Trick camera with two lenses at right angles to throw 
different images on both sides of the same film gate. 

Armani, E. (F. P. 585,759) Apparatus for taking and showing trick pictures. 

Withers, J. S. (E. P. 233,654; 234,542) Part of object only erected and re- 
produced by mirror having a contour corresponding with part of the object 
on a reduced scale, the remainder of the scenery being arranged behind the 
mirror or as a picture so that when the two are combined a complete object 
is reproduced. 

W1LKI&, N. and P. Minin. (F. P. 588,560) Use of miniature sets. 

Anderle, R. (D. R. p. 416,582) Stand for making trick pictures from several 

Griffith, D. W. (U. S. P. 1,554,210) Gauze curtain interposed between fore- 
ground and background. 

ScHtJFFTAN, E. (U. S. P. 1,569,789; 1,601,886; 1,606,482; 1,606,483) Use of one 
or more reflectors, miniature sets etc. 

Bartholowsky, J. (U. S. P. 1,574,464) Scenery on a reduced scale above the 
level of moving objects. 

Seitz, J. F. (U. S. P. 1,576,854) Specially prepared masks so that individual 
frames may be printed with scenes taken at different times. 

KoHLER, W and E. Schufftan (D. R. P. 428,589; 429,753; 429,754; 429,755) 
Object placed behind a perforated mirror which reflects another object 
on different scale. 

Williams, F. D. (U. S. P. 1,589,731) Projecting part of a view, drawing in the 
remainder of the scene and photographing the result. Cf . Weeks and Riley 

Neppach, R. and W. Voss (F. P. 604,472; D. R. P. 431,572; 432,133; E. P. 
254,925) Transparencies of scenes which may be interposed as desired. 

Continental and Overseas Trust (F. P. 611,746) Adjustable mirrors that 
may be of multiplying type so as to make a few appear a crowd. 

Aktien-Gesellschaft f. Spiegeltechnik (E. p. 230,454; 255,061; D. R. P. 
407,592; F. P. 571,567; Cf. E. P. 233,645; 234,542; F. P. 594,480). Mirror 
so near camera that the outHne through which the part scene is transmitted 
is not sharp; the outline may be an irregular edge of reflecting coat. 

Anderle, R. (D. R. P. 416,582) Scenes drawn on two bands differently il- 
luminated and combined by mirror systems. 

TwELE, O. (D. R. P. 404,511) Miniature mirror images of objects taken with 

Thoms, p. (D. R. p. 396,139) Modification of Sontag's process. 

Leventhal, J. F. AND M. Fleischer (E. P. 117,839) Enlarging cine film, 
altering these where required and photographing down again. 

Engelsmann, a (D. R. p. 409, 314) Built-up scenery with mirror reflecting a view. 

Dawley, J. S. (U. S. P. 1,463,802) Sitter taken against black background and 
another ground obtained by second exposure. 

SuTCLiFFE, G. H. (E. P. 175,020) Transparent mirror at angle of 45° in front of 
lens reflecting background, scenes or cine picture to film at same time as 
real picture is taken. 

Hammeras, O. R. (U. S. p. 1,540,213) Painted scenery on glass plate in front of 
fixed scenery. 

Trick Photography Patents — Wall 333 

ScHOLL, E. (U. S. P. 1,572,315) Making masks for multiple exposures photo- 
graphically, presumably on metal. 

Baker, F. F. (U. S. P. 1,610,410) Making mask photographically and combining 
with other films for a final picture, calls for the use of three films besides 
the final one. 

Dunning, C. D. (U. S. P. 1,613,163) Using a positive with toned shadows and 
highlights of neutral tint in front of film during exposure to a scene, which 
has a background complementary to that first used. 

Seitz, J. F. (U. S. P. 1,616,237) Making enlargement of picture and building 
out parts to produce proper shadows. 

ScHUFPTAN, E. (U. S. P. 1,613,201) Two cameras at an angle to one another 
with reflecting surface at the intersecting plane, so that one scene is re- 
flected into one camera and the other taken direct. A complementary mask 
eliminating any desired parts. 

KoHLER, W. (D. R. P. 409,974) Combination of natural scene with copy of 
another, the latter being placed in film gate. 

ScHtJFFTAN, E. (U.S.P. 1,627,295) Two lenses at about 45° to one another 
registering direct scenes and reflected images of glass on the same frame 
of a film; passing at right angles behind two objectives. 

' Brit. J. Phot. 1874, £1, 376. 

2 Ibid. 405, 430. 

^E. P. 635, 1875; Brit. J. Phot. 1875, ££, 449. 

*Brit. J. Phot. 1875, ^^,487. 

^ Photogram, 1897, 4, 65. 

«D.E.P. 100, 428, 1897. 

^E. P. 8,615, 1894. 

«E. P. 27,088, 1905; Brit. J. Phot. 1906, 53, 302, 346, 416, 472. 

«E. P. 21,781, 1906. 

^"Brit. J. Phot. 1907, 64, 927. 

"E. P. 21,950, 1905. 

^^E. P. 4,609, 1912: Brit. J. Phot. 1912, 69, 607, 619. 

^^Eder's Jahrbuch, 1915, £9, 58. 


D. C. Lindsay* 

DURING the past six years approximately two hundred theaters in 
cities well distributed throughout the United States have in- 
vested in air conditioning systems. This equipment is distinguished 
from the ordinary fan ventilation and heating equipment by the fact 
that it provides for cooling the air during the summer and, what is 
even more important, offers means of effectively establishing and 
controlling the condition of humidity. 

Assuming that the investment has proven profitable to these 
two hundred houses, there are perhaps fifteen hundred theaters in the 
same class which are immediately prepared to add such equipment 
or should make serious investigation of the relative costs and profits. 

This number will be considerably enlarged as the cost of cooling 
and air conditioning equipment is reduced through standardization 
and simplified methods. Already such a trend is evident, for a fair 
portion of neighborhood houses and a few theaters in smaller cities 
are now among the so-called air conditioned theaters. , 

The primary factor which has persuaded theater owners that 
air conditioning will prove a profitable asset has been the spectacular 
cooling of the house during the extremely hot weather of summer. 
TJiis, too, has been the primary appeal to the public. 

Though this is sufficient justification for the investment, air 
conditioning, as we shall define it, has much more to offer than the 
mere cooling during three or four sultry months. 

Theater owners, even some of those who have wonderfully 
complete air conditioning systems within their houses, have been 
prone to think of and term the equipment a refrigeration system. 
They play this feature up to the public in frosted letters nicely 
arranged about pictures of polar bears and icebergs. Fine! — psycho- 
logically, but not without its unfavorable reactions. Furthermore 
this type of advertising was used long before any theater had a system 
capable of cooling and reducing the humidity. 

Air conditioning as provided in the theater is not simply a re- 
frigeration system. The refrigeration machine is not used to make 

* Physicist, Carrier Engineering Corp., Newark, N. J. 


Air Conditioning — Lindsay 335 

ce according to the popular conception. The refrigeration machine 
has httle more to do with the system as a whole than the boiler by 
which the theater is suppHed with heat in the winter. Nor is it more 
important than the indispensable fan which is used to distribute the 
conditioned air. 

It is important, therefore, that the owner should know that a 
complete and properly installed air conditioning system provides his 
house with the means of maintaining ideally comfortable and health- 
ful conditions £very day in the year. Furthermore he has something 
to offer his patrons which cannot be approached by a theater not so 

People are learning by feeling for themselves the comfort which 
is offered in an air conditioned theater in contrast to many of our 
old buildings, particularly the legitimate houses, which are almost 
invariably stuffy and overheated even on the coldest winter day. 
We beheve that from this point of view the owners who have invested 
in air conditioning systems are overlooking a field of exploitation. 
The average person is conscious of comfort principally by contrast. 
That is why it has been easy to attract the public from the hot 
streets to the pleasant atmosphere of a properly cooled theater. At 
times when outdoor conditions do not bring this contrast boldly to the 
attention of the patron the only comparison we have is to bring to 
his mind the fact that he is comfortable in comparison to some 
experience which he has had in a stuffy overheated audience. In other 
words, the human mind is conscious of discomfort but it is necessary 
for the showman to create a consciousness of comfort by word or 
picture. For instance, it would be advisable within an air conditioned 
theater to run a trailer occasionally saying, "Isn't the atmosphere 
comfortable in here? The air within this theater is scientifically 
conditioned for your health and comfort." If the claim is true, and 
there are theaters in which this is so, the audience has thereby been 
led into a consciousness of comfort and will remember it. 

We choose, therefore, to define and describe as briefly as possible 
to motion picture engineers what air conditioning is and what it 
may be expected to accomphsh. 

Properties of the Atmosphere 

The air which we breathe is the source of hfe-giving oxygen but, 
aside from this, air serves a very important purpose as a carrier of 
heat and moisture to or away from our bodies and our lungs. 

336 Transactions of S.M.P.E., August 1927 

The temperature of air is indicated for us by the use of the 
ordinary thermometer. But, the temperature of the atmosphere is 
not a true indicator of its heat content. The heat is also dependent 
upon humidity, for heat is required to evaporate water and such heat 
is retained in the atmosphere as latent heat of evaporation. So, when 
we are considering air as a medium through which we may warm or 
cool the human body, consideration must be given to its humidity 
as well as to its temperature. 


The moisture which is associated with atmosphere in the form 
gaseous vapor is known as the humidity of the atmosphere. The 
weight of moisture associated with a given volume or a given weight 
of air is known as the absolute humidity. 

Air is said to be saturated with moisture when the space occupied 
jointly by air and water vapor contains the maximum amount of 
water vapor possible to remain in the vapor form at the existing 
temperature. The higher the temperature the greater is the quantity 
of water which can exist in a given space in vapor form. For instance, 
saturated air at a temperature of 70°F. contains 8 grains of moisture 
per cubic foot (1 grain = 1/7000 lb.) while air saturated at 85°F. 
contains nearly 13 grains of moisture per cubic foot. 

Relative Humidity 

When the atmosphere contains less moisture than is necessary 
for saturation at a given temperature, the moisture content is usually 
expressed in terms of relative humidity] that is, as a ratio of the 
weight of vapor actually present to that which might exist if the air 
were saturated at the given temperature. For example, assume that 
we have air at 70°F. containing 4 grains of moisture per cubic foot. 
By reference to tabulated data, we find that air could contain 8 grains 
of moisture per cubic foot if saturated at 70°F. It is said, therefore, 
that at this condition the air has a relative humidity of 50 per cent. 

Dew Point and Dehumidification 

If this air at a temperature of 70°F., containing 4 grains of 
moisture per cubic foot, were by some means cooled down to 50°F. 
we should find that the 4 grains of moisture would then be sufiicient 
to ^produce saturation. In this case, the temperature of 50°F. is 
known as the dew-point of the air. In other words, dew begins to 

Air Conditioning — Lindsay 


form or the moisture begins to condense at this point. If we should 
cool below 50°F., dehumidification or the reduction in moisture con- 
tent would be accomplished. Dehumidification is a subject of interest 
and one which will be discussed more fully in another part of this 

Temperature, Hiwiidity and Heat Measurements 

The most simple and reliable instrument for the determination 
of the temperature, the absolute and relative humidity, the dew-point 

Fig. 1. Two convenient forms of the Sling Psychrometer. The larger instru- 
ment has 12-inch thermometers graduated in one degree divisions. The 
smaller instrument, lying on the table, has a smaller temperature range and 
less open graduations but is a convenient pocket type. 

and the heat content of the atmosphere is the sling psychrometer, 
shown in Fig. 1. This instrument is comprised of two similar mercury 
thermometers mounted on a metal strip attached to a swivel handle 
or chain to permit whirling.. The bulb of one of the thermometers is 
covered with a fabric sheath and is to be thoroughh^ wet with water 
during observations. This is known as the wet bulb. The companion 
thermometer is called the dry bulb. 


Transactions of S.M.P.E., August 1927 

In an unsaturated atmosphere the wet bulb thermometer is 
cooled by evaporation. The amount of cooling is dependent upon 
the temperature and initial moisture content of the air to which 
it is exposed. The number of degrees which the wet bulb is cooled 
below the temperature indicated by the dry bulb is known as the 
wet hulh depression. 

A convenient set of curves has been constructed, in the Psychro- 
metric Chart, Fig. 2, to which the simultaneous wet and dry bulb 

taaft9o« vii. toi 






1 /^^S^ ^^T/i^"?^""^ 






















^7\ /^^-~~y ^^"-^/r^ 





■^ 1 



























' 1 





















, » 







1 110 













— 1 





















■S ,0 








g so 











"* 1^^ 














— -J^^t^gg^^^^^ 
















































llM IU5 Ul 


Dry Bulb Tcini>eruture 

Fig. 2. Psychometric Chart. 

observations are referred for the determination of relative humidity, 
dew-point, etc. 

It would be too involved to present here a discussion of the theory 
of the wet and dry bulb thermometer or the charts. However, the 
theory and practice are both simple and very lucid papers and in- 
structions are available for those who wish to undertake such a study. 
It is well, however, to point out here that the wet bulb temperature 
when related to the ordinary dry bulb temperature of the air is the 
most important indicator of the condition of comfort. 

Tlfie Comfort Zone 
Human comfort or discomfort depend entirely on the relation 
between the rate of heat production within the body and the rate at 

Air Conditioning — Lindsay 339 

which heat is removed. The mechanism of the human body is 
marvelous in the fact that within a very wide range of atmospheric 
conditions our body temperature is maintained at a constant point. 
The body loses heat to the atmosphere and to surrounding objects 
by radiation and convection. The rate of heat loss depends upon the 
difference between the temperature of the body and the surrounding 
air and also upon the motion of the air or the rate at which the zone 
of air immediately surrounding the body is replaced. Heat is also 
lost by evaporation of moisture from the surface of the body, the 
rate depending upon the relative humidity of the air and upon the 
motion of the air. This surface evaporation is a very important 
element in its effect upon comfort. It is through the opening and 
closing of the pores and the consequent stimulation or decrease of 
perspiration that our body temperature is controlled so accurately. 
Further heat is lost in warming up the air inhaled and in saturating 
it with moisture. 

If the condition of the atmosphere is such that heat is not carried 
away by air movement or by evaporation at the same rate at which 
it is generated, we experience discomfort and under extreme con- 
ditions, health is endangered. On the other hand if the air is so dry, 
so cold, or moving so rapidly that it tends to carry heat away from 
the body faster than it is being generated, we experience a chilling 

The American Society of Heating and Ventilating Engineers, at 
the laboratory of the Bureau of Mines at Pittsburgh, has conducted 
a long series of experiments which has laid down for us the com- 
binations of temperature, humidity and air movement which are 
conducive to the maximum state of physical comfort. For example, 
it has been shown that the average person will experience the same 
sensations of warmth under the following combinations of tempera- 
ture and humidity at a given rate of air motion: 

Dry Bulb Temp. Relative Humidity 

80°F. 12 per cent 

75° 38 " " 

70° 73 " " 

67° 100 " " 

All of these combinations of conditions are classified arbitrarily as 
being of the same effective temperature. That is to say, they create the 
same sensation. In this set of examples, the effective temperature 
is 67°F. 


Transactions of S.M.P.E., August 1927 

Effective temperatures have been superimposed or plotted upon 
a Psychrometric Chart such as is shown in Fig. 3. OutUned upon this 
chart is an area known as the comfort zone. It has been found that 
combinations of conditions of temperature and humidity lying outside 
of this zone are not comfortable to the average person. The line of 
maximum comfort, it will be noted, is the 64° effective temperature line. 
Some authorities are inclined to place this Une somewhat higher in 



70 75 


Fig. 3. The Comfort Chart for Humans at Rest. 

the scale. The particular comfort chart shown here is for com- 
paratively still air. If the velocity of the air were increased the result 
would be to tip the effective temperature lines more toward the 
horizontal. It would then be found that the same conditions of 
comfort would be produced for a given dry bulb temperature with 
a higher relative humidity than that shown on this chart. 

The effect of air motion in producing coohng increases with the 
velocity at all temperatures below 98.6°F., the normal body tem- 
perature. Above this point increased velocity naturally tends to 
convey more heat to the body and to increase the effective tem- 

Air Conditioning — Lindsay 341 

The value of such data as this cannot be over-estimated for 
they have given us very definite Kmits within which to operate in the 
creation and control of a comfortable atmosphere. 

Those who have had experience in observing the conditions of 
comfort within theaters or pubHc buildings have found definite 
verification for this range of comfort temperatures. It is an interesting 
fact that whenever the limits of the comfort zone are exceeded 
individuals in the audience begin to fan themselves or give other 
evidence of discomfort. A further interesting fact is that the famiUar 
and unpleasant odors typical of a crowded room develop immediately 
when the upper range of the comfort zone is exceeded. 

Air Conditioning 

Air conditioning is the science of creating and automatically 
controlhng stipulated conditions of temperature humidity and air 
movement within buildings, regardless of outdoor conditions. 

For more than 25 years engineers specializing in this field of 
work have been developing equipment and devising methods for 
controlling air conditions and the effect upon materials and manu- 
facturing processes in a large variety of industries. So the science 
is by no means new though its appUcation in the theater and public 
building field dates back scarcely a half dozen years. 

An Engineering Problem in the Theater 

Though there were many special problems to be solved in 
applying air conditioning to the theater the principles and much 
of the equipment had undergone long trial and development within 
the industries. 

It is perhaps well to say here that under the term air conditioning 
we are not including simple ventilation systems which are designed 
solely to change the air within the building. These are not without 
merit but they constitute only a portion of an air conditioning system. 

Given the air conditioning equipment and methods developed 
in the numerous industrial apph cations and given the limits of 
comfort as stipulated by experience and the researches which we 
have mentioned; the application of air conditioning within the 
theater has been one of engineering adaptation. 

The very nature of the usual theater structure has, however, 
offered enough unique and difficult problems to demand the utmost 
in engineering background and skill. Here in a single enclosure are 

342 Transactions of S.M.P.E., August 1927 

to be gathered anywhere from a few hundred to six or seven thousand 
people for a period of 12 hours per day. Myriads of Hghts are to give 
off heat. The ceiHng in some houses is full six stories above the 
orchestra. An immense cantilever balcony extends half way over the 
orchestra to obstruct air circulation. A vast lobby and foyer fre- 
quently packed with standing patrons offer an added problem. 

The chief consideration for the air conditioning engineer is the 
manner in which a sufficient quantity of properly conditioned air 
may be supplied to and uniformly distributed within such an en- 

An Outline of Theater Air Conditioning Practice 

Let us outline the ideal conditions which should be maintained 
within a theater and follow the process of their accomplishment. 

1. The air should be relatively clean, washed or filtered to 
protect the health of patrons and to preserve the beauty of the 
decorations and draperies. 

2. During the summer a temperature of approximately 75°F. and 
a relative humidity of 55 per cent is in most cases comfortable, though 
there is a tendency now to carry a sfightly higher temperature and a 
correspondingly lower relative humidity. During the winter a 
temperature of approximately 70°F. with a relative humidity of from 
35 to 50 per cent is found practicable and comfortable. 

3. The proper quantity of conditioned air to be supplied to the 
theater is generally conceded to be about 30 cubic feet per minute 
per person. This is not based upon the quantity of air which one 
breathes in a minute. The average person inhales little more than a 
cubic foot of air per minute. The quantity of air is based rather upon 
the heat dissipation of the average individual which is sufficient in 
one minute to raise the temperature of 30 cubic feet of air approxi- 
mately 9°F. 

4. Finally, this quantity of air must be carried to and distributed 
uniformly throughout every portion of the building. Since the air 
is cooled, the greatest care must be used in regulating the velocity 
and the direction at which it is delivered in order to avoid draughts. 
In other words, reference must be made to the comfort chart and 
the velocity of air delivered carefully adjusted to establish a comfort- 
able combination with the existing temperature and humidity. 

5. A certain quantity of fresh outdoor air should always be a 
part of the air deHvered to the house. The practice in this regard 

Air Conditioning — Lindsay 


varies rather widely. Some cities have ordinances which require that 
all of the air delivered to the theater be fresh outdoor air and forbid 
recirculation of any portion of the air within the building. Such a 


Fig. 4 

A. The Carrier Centrifugal Refrigeration unit wliicli cools the water for 
the spray chamber. 

B. The spray chamber or dehumidifier where the air is dehumidified, 
cooled and cleansed. 

C. The centrifugal fan which draws the air through the spray chamber 
and passes it through metal %icts to the theatre. 

D. The large metal ducts through which conditioned air is passed to the 
ceilings of the theater. 

E. The downward diffusion outlets through which the air is diffused over 
the audience, reaching the Breathing Zone first with complete absence of 

F. The chambers beneath the balcony and orchestra seats into which the 
air is drawn from the theater. 

G. The large metal ducts through which the used air passes back to the 
spray chamber to be rewashed, cooled, dehumidified and mixed with fresh air. 

requirement is absurd and would subject the owner to a prohibitive 
expense either to heat or to cool his theater. Air conditioning en- 
gineers and numbers of health authorities have pretty generally 
agreed that a constant minimum dilution of 25 per cent of fresh out- 
door air or approximately 8 cu. ft. per minute is ample from every 
point of view. 


Transactions of S.M.P.E., August 1927 

We have outlined five general problems which are to be solved 
in establishing ideal air conditions within the theater. 

Consider now, a theater completely equipped with a typical air 
conditioning and refrigeration system. The cross section of such a 
building and its air conditioning equipment are shown in Fig. 4. 
Assume that we have an outdoor temperature of 85°F. and wet 

Fig. 5. Humidifier or Dehumidifier showing automatic dampers for the 
admission of fresh and recirculated air on the right, the spraj chamber; the 
pump; automatic control instruments and valves and on the left, the fan 
which discharges the conditioned air to the duct system leading to the various 
portions of the building. 

During the summer, the water is cooled by refrigeration and in turn cools 
the air passing through the chamber. The cooling also causes the excessive 
moisture to be condensed. 

During the winter, the same chamber serves to wash and purify the air 
and contrary to the summer practice adds the proper amount of humidity 
to the air for healthful comfort. 

bulb temperature of 75°F. This is not an unusual summer day. Under 
these conditions the outdoor relative humidity is found on the 
Psychrometric Chart to be 63 per cent. The dew-point or condensa- 
tion temperature of the outdoor air is about 71°F. We wish to 
establish, as outlined in No. 2 of the requirements given above, a 
temperature of 75°F. and a relative humidity of 55 per cent. We find 
from the Psychrometric Chart that this condition calls for a dew- 

Air Conditioning — Lindsay 345 

point of approximately o7°F. in the theater. We have not only to 
cool the air from 85° to 75° but we have to dehumidijy, that is, to 
condense sufficient water out of the air so that the dew-point is 
lowered from 71° to 57°F. Observe then how this is done. 

We have as a part of the air conditioning equipment a spray 
chamber such as shown in Fig. 5 within which hundreds of small 
nozzles are atomizing perfect clouds of water. During summer 
operation the water supplied to this chamber is cooled by refrigeration 
to a temperature of about 45°F. By means of the large centrifugal 
fan, air is drawn through this chamber in intinaate contact with the 
water spray. Here it is completely washed, meeting requirement 
No. 1 stipulated above; here also it is cooled to a temperature of 
about 50°F. The air has given up its heat to the water and the water 
temperature has risen about 5°. Observe also, that in cooling the air 
to this extent we have gone below the initial dew-point of the outside 
air. Therefore, water vapor must have been condensed out of the 
air. In other words, we have reduced the dew-point of the entering 
air from 71° to 50°F, 

From this chamber the air is drawn into the fan. It would not 
be desirable to admit air at 50°F., saturated as it is, upon leaving 
the spray chamber. Some economical means must be adopted for 
raising the temperature of the air and incidentally for reducing its 
relative humidity. One ver^^ economical method of doing this is a 
patented scheme of recirculation. Some warm air is drawn from the 
theater and intermixed with the cold saturated air at the intake of 
the fan. The mixture has a temperature ranging from 62° to 65°F. 
and the dew-point of this mixture has been slightly increased by the 
vapor carried in the warm recirculated air. The fan then delivers the 
air through a metal duct system to outlets carefully located in the 
high ceiling of the theater, in the ceiling beneath the balcony and 
at other points throughout the building where cooling is required. 
The location and the design of the outlets has been a matter of careful 
investigation on the part of air conditioning engineers. The air de- 
livered through these is not blown into the building but is delivered 
at adjusted velocities and is so directed that the result is one of 
diffusion, a blanket of air, passing downward over the audience. 

The temperature of the air lea\dng the outlets ranges from 62° 
to 65°F, In mixing with the warmer air of the theater, gathering up 
heat which has been given off by the occupants, by lights and through 

346 Transactions of S.M.P.E., August 1927 

infiltration from out-of-doors, it reaches the breathing zone at our 
stipulated temperature of approximately 75°F. 

After passing over the audience, a portion of the air is withdrawn 
through mushroom openings beneath the seats or through openings 
arranged at other low points. This air is drawn back to the spray 
chamber to be rewashed and re-cooled or a portion of it may be 
mixed with the stream of newly washed air, as previously explained. 

Since an adjusted quantity of fresh outdoor air is at all times 
being drawn into the air conditioning system, a like quantity is being 
discharged from the theater. In a properly balanced system the over- 
flow occurs outward through the lobbies and exits. Thus the air 
within the building has a very slight outward pressure. The old 
bothersome inward draughts are eliminated and the commonly used 
glass screen to protect the audience at the rear of the orchestra seats 
is no longer needed. 

This system of air circulation is known as the downward diffusion 
system and is pretty generally conceded by air conditioning engineers 
to be far superior to the former practice of admitting conditioned air 
at the floor line. 

Automatic instruments located in the supply and return airducts 
are subjected to the incoming and outgoing conditions of the air and 
react upon systems of dampers and valves to produce the proper 
temperature and humidity at the breathing zone. The automatic 
instruments which have been developed for this purpose are positive 
and extremely accurate. Once properly installed they are almost 
fool-proof and require practically no attention. 


In describing the spray chamber within which the air is cooled 
and dehumidified we mentioned that refrigeration is necessary for 
reducing the temperature of the water to about 40° or 45°F. Most 
any form of refrigeration machine can be used to cool water. There 
are requirements, however, within a building, such as a theater, 
which narrow the selection of refrigeration equipment down to two 
types. The refrigerating medium must, in the first place, offer no 
hazards to congregated people. This immediately bars the use of 
the familiar refrigerants, ammonia, sulphur dioxide and such gases 
as are offensive or dangerous. 

The second requirement is compactness, because most theaters 
are hmited in available space for equipment and the property upon 

Air Conditioning — Lindsay 


wliich they are constructed is usually valuable. Again, compactness 
will offer a decided saving if excavation is required. 

The two refrigeration systems which have found successful 
adaptation in the theater have been the reciprocating machines using 
carbon dioxide as a refrigerant and the more recent development 
Carrier Centrifugal Refrigeration, using as a refrigerant, "Carrene" 


Fig. 6. A modern type York carbon dioxide refrigeration compressor. Tlie 
piping separators and other auxiliary equipment leading to the expansion and 
condenser coils are not shown. The banks of pipe coils in which the com- 
pressed is condensed and the expansion coil where cooling is produced are 
usually located at a distance from the compressor. 

(dichloromethane C H2 CI2), one of a group of stable liquid chemicals 
which have been found suitable for centrifugal compression. 

The fundamental theory of all refrigeration systems is the same. 
Expansion or evaporation or boihng are processes which absorb heat 
in their performance or, looking at it another way, which produce 

Carbon Dioxide 

Carbon dioxide is a gas at all ordinary atmospheric temperatures 
and pressures. In the cycle of refrigeration, its pressure is increased 


Transactions of S.M.P.E., August 1927 

to 1,000 lbs. or above by a reciprocating compressor; that is, a com- 
pressor which performs its work by the action of a piston within a 
cylinder, illustrated in Fig. 6. After compression to this degree, the 
very dense gas is caused to liquefy or condense within a double pipe 
system through which water from the city mains or from a cooling 
tower is circulated. The condensed carbon dioxide or dense gas then 
passes from the condenser to expansion coils which are surrounded 
by the water to be cooled for the spray chamber. Within these coils 





Fig. 7. Diagramatie arrangement of the Carrier Centrifugal Eefrigeration 
Unit showing assembly of the cooler, compressor and condenser and the com- 
plete cycle of refrigeration. 

the expansion or boiling of the carbon dioxide takes place with the 
consequent absorption of the heat from the water which it is intended 
to cool. 

Centrifugal Refrigeration and the New Refrigerant 

Carrene, the new refrigerant used in centrifugal refrigeration, is 
liquid at all normal atmospheric temperatures and pressures. It can 
be carried in open containers. The cycle through which this re- 
frigerant is carried to produce cooling is as follows. 

Within a vacuum-tight compartment known as the evaporator 
the liquid refrigerant is allowed to flow over a large number of bronze 
tubes. (See (A), Figs. 7 and 8.) Through these tubes the water to 
be cooled for the spray chamber is circulated. By means of a cen- 
trifugal compressor, which in many respects is similar to an ordinary 

Air Conditioning — Lindsay 


centrifugal water pump, a vacuum of approximately 25 inches of 
mercury is maintained within this cooling compartment. (See (B), 
Figs. 7 and 8.) At this reduced pressure the boiling point of the liquid 
refrigerant is largely reduced. This vigorous boiUng occurs on the 
outside of the tubes and heat is absorbed from the water which is 
being circulated to and from the spray chamber. The vapor which 

Fig. 8. A complete Carrier Centrifugal Eefrigeration Unit. (A) The evap- 
orator or cooler; (B) The Centrifugal compressor; (C) The condenser. A unit 
• this size would be used to cool and dehumidify a 1000 seat theater. 

results from this boiling is drawn into the centrifugal compressor. 
Through the several stages of the compressor the pressure of the 
vapor is raised to such a point that it is possible to cause condensation 
of the vapor by water at such ordinary temperatures as are available 
within city water supplies or from cooling towers. This condensation 
is produced in a compartment within which bronze tubes are arranged 
in exactly the same manner that we have described for the cooling 
compartment. (See (C), Figs. 7 and 8.) The refrigerant having been 
reconverted to a liquid then flows back to the cooHng compartment 
to be re-used, thus completing the very simple cycle. 

350 Transactions of S.M.P.E., August 1927 

Centrifugal Refrigeration and the liquid refrigerant are well 
adapted to the problems involved in the application of air condition- 
ing. The harmless nature of the refrigerant, the extreme compact- 
ness of the machine and the fact that the refrigerant does not leave 
the closed circuit within the machine itself are the novel features 
which have favored its adoption in many theaters. 

The Refrigeration Season 

A theater having a complete air conditioning system including 
refrigeration should operate the refrigeration machine at all times 
when the outdoor wet bulb temperature exceeds 55°F. The wet bulb 
temperature is the temperature which would be assumed by the 
water in the spray chamber if recirculated without means of cooUng. 

During a period of about four months of each year, nearly every 
city in the United States experiences a predominating number of 
days at which the wet bulb temperature exceeds 55°F. 

Air Conditioning in Winter 

We now turn to a problem of conditioning the air on a typical 
winter day. Assume that the outdoor temperature is 32°F. and 
that the outdoor air is saturated with moisture, as it frequently is at 
this temperature, so the dew-point of the air brought into the spray 
chamber from out of doors is likewise 32°F. We have stipulated in 
our requirements for comfort in the theater a winter condition of 
70°F. and a relative humidity of from 35 to 40 per cent. From the 
Psychrometric Chart, we find that this condition establishes a dew- 
point of 42°F. In other words, our requirement within the spray 
chamber during the winter is to humidify the air, that is, to add 
moisture rather than to dehumidify. Under the conditions assumed, 
we can accomplish this by heating the fresh air taken in to a temper- 
ture of 50°F., which raises the wet bulb temperature of the incoming 
air to 42°F. and it is at this point that the air will become saturated 
within the spray chamber. 

As in the summer time, a controlled amount of re-circulated 
v/arm air is mixed with the air which passes through the spray chamber 
so that the condition of the air delivered is approximately 70°F. and 
the relative humidity is approximately 35 per cent. 

It is interesting to note that under all conditions during the 
winter when the theater is well filled, the air conditioning problem is 
still one of cooHng rather than of heating. The air delivered from the 

Air Conditioning — Lindsay 351 

diffuser outlets is, as during the summer, at a temperature of about 
62°F. and in passing down over the audience collects the necessary- 
heat to raise it to a temperature in the neighborhood of 70°F. 

In the theater having complete air conditioning equipment there 
is practically no use for any direct radiation heaters. Occasionally a 
bank of direct radiators is placed in the vestibule which opens directly 
to the outdoor atmosphere. The elimination of direct radiation within 
the building has many advantages. It ob\dates the local overheating 
of certain sections of the theater where steam pipes or radiators might 
be located. Automatic control of the heaters located within the ducts 
through which the air is carried acts quickly and accurately. An 
interesting analysis of the fuel saving accomplishment by air con- 
ditioning during the winter could be made if we had space here to do 
it. It is enough to say that little or no steam is required or used in 
heating the building, except in the warming up before the crowd is 
admitted. Once the theater is occupied the heat given off by the 
audience is sufficient to overheat the house and, as we have said, 
there is a cooling problem to be solved. 

The Cost of Air Conditioning 

The theater o\yner is naturally interested in the cost or the 
economic side of complete air conditioning equipment. This is logical 
and the only basis upon which he can consider it. It is possible here 
to give only some very general figures. To date, most of the air 
conditioning systems in theaters have required an initial expenditure 
approximating $32.00 per seat. This includes a complete conditioning 
system, the refrigeration machine and all expense to which the owner 
is placed in the alteration of an old building or in adapting a new 
structure to the equipment. Frequently the figure has been as much 
as 25 per cent below this amount. 

In certain typical installations which we have investigated, the 
cost of operation per day per seat throughout the year averages 
between 3 and 3^ cents. This includes depreciation, the engineer's 
salary, power, steam, water, interest on the investment and all 
incidentals. Naturally, the cost of operation during the winter is 
much less than in the summer. 

On the assumption that each seat is occupied at least twice a 
day, and this is below the reasonable expectation of the firstclass 
house, the cost per ticket to make a patron comfortable is slightly 
over 1| cents. 

352 Transactions of S.M.P.E., August 1927 

While considering this cost, the owner should also consider that 
many items which are included therein are those which would have 
to be borne under any circumstances. The system replaces the 
ordinary heating, air washing and fan system that might be installed 
and this is also true in the employment of an attendant or attendants. 
Careful estimates of the costs and maintenance of the ordinary air 
washing, heating and ventilating system show a cost of approximately 
2 cents per day per seat. The expected cost per patron is 1 cent. 

Thus the difference in cost of complete air conditioning and the 
usual air washing, heating and ventilating amounts to something 
hke 1/2 cent per expected patron. 

The difference per day per 1000 seats is approximately S15.00. 
A daily sale of 43 additional tickets absorbs this excess. 

Experience has shown in theaters having complete air con- 
ditioning that the increase in summer patronage makes this expense 
extremely insignificant. Official box office reports show in not a few 
instances an increase of from 50 to 100 per cent in average summer 
receipts accredited primarily to the air conditioning system. 
Furthermore, these same houses have shown a notable increase in 
receipts during the intermediate and winter seasons. 

This analysis and comparison must not be understood as a sale 
argument. It is offered with complete fairness and with the sole object 
of indicating to the owner the factors which must be dealt with in 
considering the undeniable fact that comfort of patrons is an asset. 

Air Conditioning in the Film Lahoratory 

Here we approach an important appHcation of the science of air 
conditioning which far antedated atmospheric control in the theater. 

We have pointed out in the first paragraphs of this paper that air 
conditioning found its inception in the necessity for artificially 
estabhshing and controlhng suitable atmospheric conditions for the 
efficient and successful accomplishment of many industrial processes. 

From the beginning of the development of the photographic 
film art, it has been necessaiy to use many precautions in protecting 
the delicate surface of the fihn as it passes through the many opera- 
tions prior to, and after, exposure. 

It has always been necessars^, for instance, to protect the fihn 
from a dusty atmosphere which would cause particles to adhere to 
the adhesive gelatine surface while the film is in a wet state. The 
film laboratories have long since adopted numerous measures for 

Air Conditioning — Lindsay 353 

filtering or cleansing the air admitted to their process rooms and 
manj^ laboratories have sought rural locations where the outdoor 
atmosphere is comparatively free from dust. 

As the art of film making has advanced and as the demand for 
quantity production has increased together with the necessity of 
meeting production schedules, the need for creating and controlling 
suitable atmospheric conditions has become a decidedly more im- 
portant factor. 

The follomng are points in the appHcation of air conditioning 
toward the improvement in the production of motion picture film. 

1. Wet coated film must at all times be protected from an 
atmosphere containing soHd particles of any form. This imposes the 
requirement for the complete and efficient filtration or washing of all 
air admitted to developing, drvdng or printing departments. 

2. The atmosphere to which a dried film is exposed for any 
considerable period should have sufficient humidity to maintain the 
pUabihty of the fihn. This is to avoid brittleness and the chance of 
breaking when the film is subjected to handling or is passed through 
printing or projection machines. 

3. Films, negative and positive, which are to be run through a 
printing machine, should have previously been exposed to a humid 
atmosphere for a determinable period, and the printing operation 
should be conducted in an atmosphere of sufiicient humidity to pre- 
vent the generation of static electricity'- with its consequent marking 
of the sensitized surface.* 

4. Film drying rooms or cabinets should be pro\dded with 
equipment to establish and maintain determinable conditions of 
temperature and humidity. Through controlled rates of drying film 
curling and buckhng can be largely eliminated and the danger of the 
distortion of the gelatine surface as a result of excessive conditions 
of temperature and humidity may be prevented. 

5. Means should be available to automaticall}^ control the tem- 
perature of developing and fixing solutions and wash water. This 
does not come primarily under the heading of air conditioning but 
in some of the modern equipped laboratories such a system operates 
in conjunction with the air conditioning system. It is also desirable 
to maintain controlled conditions of temperature and humidity within 
the developing rooms. 

* See "Static Markings on Motion Picture Film", by J. I. Crabtree and C. 
E. Ives.— Trans S. M. P. E. 21, 1925, 67. 


Transactions of SJI.P.E., August 1927 

In outlining these desirable possibilities, we have given thought 
to the fact that all laboratories do not operate on a sufficiently large 
scale to justify all of the elaborations of equipment outlined. We 
choose, therefore, to suggest in their order of importance the measures 
which a laboratory might adopt for atmospheric control. 

Air Filtration 

The first requirement is, of course, to dehver air to the laborator^^ 
completely free from dust or sohd matter. The most simple and 

I H =H 


Fig. 9-A. The Sectional Air Filter Dry Impingement Type. Air path is shown 

on right. Each perforated plate is covered with a dry fibrous material to 

which the dust adlieres upon impingement. 

inexpensive means of accomplishing this is to draw the air through 
one of the several types of commercial air filters and thence to dehver 
the air to the room or to the drying cabinet by means of a fan and 
duct system, the selection and design of which would, of course, 
depend upon individual requirements. 

There are five general types of commercial air filters, illustrations 
and descriptive captions of which are shown in Fig. 9. We cannot 
attempt here to discuss the relative merits of these various devices. 

Air Conditioning — Lindsay 












\Ai DE/^^SITY 



Fig. 9-B 

The Viscous Coated Air Filter sectional Type. Filtration is effected by 

dipping the unit in a viscous fluid. Periodic removal of the sections is 

required for cleaning and recoating. 

We may say, however, that we beheve any one of these types will 
effectively clean the air for commercial work and that the preference 
in selection may depend first upon cost, upon comparative efficiency 


Transactions of S.M.P.E., August 1927 

or air resistance, upon ease of cleaning and the necessary frequency 
of cleaning or replacement. 

The Air Washer 

The alternate selection which might be made for simple dust 
elimination and one which, though more expensive, offers some 

Fig. 9-C 

The Multi-Pocket Cloth Air Filter. Dry Type. Each cloth envelope is an 

independent unit stretched over a frame. The lower edge of cloth and frame 

are immersed in oil which serves as a seal. Air passes through the entire 

outer surface and out at the slot in the bottom. 

advantages in its possibihty of partial humidity and temperature 
control, is the air washer or water veil system of air cleansing. 

Such a system is comprised of a metal chamber within which 
water is minutely atomized through nozzles arranged in vertical pipes 
as illustrated in Fig. 10. An air washer will produce some reduction 
in temperature within the laboratory during the summer and has 

Air Conditioning — Lindsay 


The Viscous Coated Air Filter Continuous, Self Cleaning Type. The filter 

elements are periodically rotated by the motor carrying the sections into 

the bath of viscous fluid in the base. 

the advantage of relieving the extremely arid condition which is 
created within artificially heated rooms during the winter. The 


Transactions of S.M.P.E., August 1927 

effectiveness in dust elimination compares favorably with non- 
humidifying air filters. 

The humidifier is similar in almost every respect to the air washer 
except that it is designed to use a greater quantity of water and is 

Fig. 9-E 

The Viscous Coated Air Filter Self Cleaning, Stationary Element Type. The 
filter element is composed of vertical tubes having a stream-line section. 
Viscous fluid is periodically pumped up from tank at bottom and flooded 

over elements. 

equipped with instruments to effectively establish and control 
temperature and humidity in the rooms to which the air is being 

This equipment is particularly desirable since it meets in nearly 
all respects the requirements laid down in Nos. 1 and 2 of our enumer- 
ated advantages of air conditioning as given above. Such equipment 
can be adjusted to maintain the desirable moisture content in the 

Air Conditioning — Lindsay 


Fig. 10 

film stock and to maintain the proper condition of humidity in the 
printing room to ehminate static marking. 

The greatest demand for such control comes, as previously in- 
timated, during the winter season. The outdoor air during the 


Transactions of S.M.P.E., August 1927 

winter carries very little moisture, and upon being artificially heated 
to indoor temperatures, a condition of exceedingly low relative 
humidity is established, which is highly conducive to static pro- 

It may be implied that there are periods during the humid 
summer season when a humidifier will not be required except as an air 
cleanser. This is so and it is not infrequent for laboratories to have 
in their equipment a combination of air filters and a humidifier. This 
permits the shutting off of the water spray when humidification is 
not required, the air filters serving to cleanse the air. 

4' rir. t^K/^<i-!^ur^ In 4^ 

e*&w?T!C5 of alf 

«-«-»— ~~.>-^ '---I . , . i , |„-, „ , n . \^«m > .I I I . I I H . I I ■ ii|i.r.,iprr..|. .i»i. , .. r , m«m,. ■/ 

5tp 9nrMfl*}o loi p(M(^*tti ^B0fW8-<S V 


^^ RfiQ^ 'hurnace. filizr^^ 4^' P.' tf € a . 1^1.^ .^i ce r > 1 le v -\ 

Fig. 11. A Simple Test for Effectiveness of Air Filtration. The surface of 
the porcelain plaque is smeared with a thin coat of vaseline and exposed to 

air stream. 

Complete Temperature and Humidity Control 

We come finally to the most elaborate equipment for air con- 
ditioning with which a laboratory could be provided. Several of the 
larger laboratories have such equipment, others are having such 
installations made. We cannot do better than to describe here the 
features of an installation that is now in process at the laboratories 
of the Attica Film Corporation in New York City. 

Object of Air Conditioning Equipment 

These laboratories are to be devoted primarily to the production 
of news films. It is, therefore, necessary to provide means of turning 
out finished film in good condition in the shortest possible period. 
'The plans for applying conditioned air in this laboratory include the 
automatic control of temperature and humidity in four "Duplex'' 

Air Conditioning — Lindsay 361 

drying cabinets, one large drum-drying room, two printing rooms and 
the wet end of the machine developing room. The air conditions to 
be maintained in these various departments are subsequently 

Since refrigeration is to be used for the coohng of the air in these 
rooms during certain seasons, the same refrigeration unit will be 
utihzed to automatically cool and control the temperature of de- 
veloping solutions. 

Provision is also being made to automatically warm the develop- 
ing solutions to a fixed temperature during the winter. 


The air conditioning and drying equipment which will go into 
this laboratory consists of two water spray chambers which are to 
serve according to the season, either to cool and dehumidify the air 
or to warm and humidify the air suppHed to the various departments. 

Two fabric envelope type air filters are being installed on the 
discharge side of each spray chamber. These are to serve as a final 
assurance against dust and will permit, on occasion, the operation of 
the fans without the use of the water spray. 

A Carrier Centrifugal Refrigeration Unit is provided for the 
cooling of the water supplied to the spray chambers in order to pro- 
duce air cooling and dehumidification during the summer. This unit 
will also serve to cool the developing solutions. 

There are to be four "Duplex" cabinet drying machines, each 
of which is equipped with an individual fan, heater and temperature 
and humidity control instruments. 

Provision is made to supply by automatic control, fresh air to 
the drying cabinets from one of the spray chamber and filter systems. 

The cabinets are thus completely protected from the admission 
of dusty air. 

One large drum-drying room is supphed with automatically 
conditioned and filtered air deHvered at high velocity through a row 
of patented ejector nozzles located near the ceiling. This provides 
for the rapid drying of films on several large drums in an open room. 

Conditioned air is to be supplied under automatic temperature 
and humidity control to two small printing rooms. 

Conditioned air is also being supplied to the wet end of the 
machine-developing room primarily for the purpose of ventilation 
and the health and comfort of the operators. 

362 Transactions of S.M.P.E., August 1927 

Specification of Results 

The following guarantees have been made by the engineers who 
have designed and are installing this air conditioning equipment. 


1. Air movement and humidity within the four "Duplex" drying 
cabinets are to be so controlled that drying can be successfully and 
satisfactorily accomplished at the rate of 30 feet per minute; this 
provides 240 feet of film per minute passing through the four cabinets. 

2. The cabinets are to be so equipped that film may be dried at 
the rate of 50 feet per minute or a total of 400 feet per minute for 
the four cabinets. This is under the assumption that temperatures 
between 85 and 90°F. will be used and under these circumstances 
the operators assume responsibility for the quality of the film. 

3. The air supply, heating equipment and automatic controls 
in the drum-drying room are to be such that 4200 feet of film can 
be dried on the drums in a period of 22 minutes at a temperature of 

4. The equipment in the drum-drying room will also provide the 
possibility of drying 4200 feet of film in a period of 10 minutes at 
temperatures between 85 and 90°F. Here again, however, the 
operators assume responsibility for the quality of the film. 

Printing Rooms 

1. The equipment is designed to maintain within the printing 
rooms temperatures not exceeding 75°F. when outside temperatures 
do not exceed 95°F. or an outdoor wet bulb temperature of 75°F. 

2. It is planned that the equipment shall provide at all times 
within the printing rooms relative humidities between 65 and 70 
per cent. Higher humidities than this may be maintained if desired. 

3. The equipment provides means of automatically heating the 
printing rooms to a temperature of 70°F. in zero weather. 

Temperature Control of Developing Solutions 

1. The centrifugal refrigeration unit which is provided for cooHng 
the water supplied to the spray chambers during the summer is also 
to be utihzed to cool 100 gallons of developing solution per minute 
not less than 2° from the temperature at which it returns to the 
system from the developing tank. 

Air Conditioning — Lindsay 363 

2. Through automatic control, the developing solution is to be 
dehvered from the cooling tank at a temperature of 68°F. with an 
allowable variation of 1°F. 

3. Equipment is provided which is to automatically warm and 
maintain the developing solution at 68°F. during the winter. 

Dust Removal 

1. The equipment is guaranteed to remove all dust from the 
conditioned air circulated within the printing rooms, the drum-drying 
room and the drying cabinets. 

Thus we have outlined the full equipment and application of air 
conditioning within the film laboratory. Beyond this is a matter of 
size and elaboration. For instance, conditioned storage rooms could 
be provided, in which a definite temperature and humidity could be 
maintained, for the purpose of retaining the pliability of the film. 

No doubt, in the laboratory which we have described, a con- 
siderable stock of film will be kept on hand within the conditioned 
rooms so that all of the film handled will have a sufficient amount of 
moisture to be pliable. The films, sealed within metal boxes, in such 
a conditioned laboratory will go forth for use in a pliable condition. 


Mr. Crabtree: What is the advantage of dichloro-ethylene 
over ammonia or carbon dioxide. Is it because if there is a break in 
the line it is not so dangerously poisonous? 

Mr. Lindsay: Ammonia is out of the question in a theater. 
Carbon dioxide is harmless unless it diffuses into a house to such an 
extent as to produce suffocation. Dichloro-ethylene is a liquid, 
not a gas, at ordinary atmospheric temperatures and pressures. The 
boiling point depending on the purity of the liquid, runs from 120° 
to 180° F. Its density is about three and a half times that of air, 
which makes it adaptable to centrifugal refrigeration. It could be 
done with air, but would require a cumbersome equipment. We are 
limited as to size. The advantages are its safety, for if anything should 
break the machine, only liquid would run out. It is confined to a 
space about one-fifth that of any present refrigerating system. 

Mr. R. C. Hubbard: Is the question of cleaning air by oil 
filters dealt with? 

Mr. Lindsay: I have not gone extensively into that point; but 
as some editing of my paper has to be done this and other matters 

364 Transactions of S.M.P.E., August 1927 

as suggested here will be dealt with. We are using oil filters and oil 
seals in connection with air washers in laboratory work in order to 
doubly assure the removal of dust and particles of soot. There is 
nothing yet which will completely remove smoke, unless one uses 
electrostatic elimination. 

Mr. Stewart: In Mr. Faulkner's paper, which he read at the 
last spring meeting, he referred to the heat of the projection room. 
He correctly claimed that much of the dirt and dust of the theater, 
as seen in the rays of light from the projector, are attracted to the 
carbons of the arc, driven on to the film and cause scratching. In 
your ventilating could you not direct this dirt-laden air from the 

Mr. Lindsay: We are doing that. The projection room is con- 
ditioned, and there is a separate exhaust system going to each 
projection scheme. In all theaters that we have recently fitted 
out the heat is carried away from the lamp and conditioned air 
supplied to the machine. 

Prof. Wall: Is there any danger of hydrolysis of the dichloro- 
ethylene with the evolution of hydrochloric acid and etching of all 
metal parts? There is hydrolysis in contact with water. 

Mr. Lindsay: We have not experienced any. We get free hydro- 
chloric acid if we burn it, but it burns with a very slow flame. 
Methylene is, of course non-inflammable. In order to guard against 
rust where water has got into a machine, we have taken the oc- 
casion to coat some of the machines with zinc. 


By F. Benford 

In this paper no attempt is made to give a complete analysis of the low 
pressure mercury lamp, but attention is confined to a few of the characteristics 
that are of most importance to the user of the lamp. A brief description of the 
physical construction of the lamps used in the test work is followed by a spectro- 
photometric determination of the energy distribution in the spectrum. Data on 
tube brilliancy and on causes of depreciation are given in their relation to photo- 
metric outputs, and some typical figures for tube life are discussed. The photo- 
metric distribution curves of both A.C. and D.C. lamps are given, both as bare 
tubes and as units complete with reflectors. The section on electrical character- 
istics gives some recent test data, and several of the most important reactions of 
the tube to ambient temperature are used to call attention to the factors to be 
watched during photometric tests. The concluding section gives briefly some of 
the conflicting phenomena that have contributed not a httle to the present 
uncertainty about the reactions of the human eye under this hght. 


The mercury arc in some of its many forms is to most of the 
members of the Society a light source with which they come into 
daily contact. It can hardly be brought before you as a novelty or 
a new contribution to the field of illumination, for the mercury arc 
is a true contemporary of the motion picture art and their two his- 
tories are so intertwined as to seem like one. But within the last two 
years a considerable amount of research has been carried out with 
the idea of getting a more intimate knowledge of this interesting, 
and highly individualistic Hght. As a result of these photometric 
researches and investigations, which are mostly of a rather elemental 
nature, several interesting and important features were brought to 
Ught. It is highly probable that some of the discoveries are really 
rediscoveries; but they will be here recorded because they will be 
new to a majority of the members. 

The scope of the investigations included photometric, electric 
and temperature characteristics and at the present time preparations 
are under way to carry the work into the near ultra-violet region 
that is of such importance to the photographer. This latter part of 

* Illuminating Engineering Laboratories. General Electric Co. Schenectady. 


366 Transactions of S.M.P.E., August 1927 

the work is not far enough advanced to give the careful analysis 
that the standards of this Society demand, and therefore the present 
paper is limited strictly to visible radiation. 

1. Physical Construction of Lamp 

The tubes used in these experiments are 1 inch in outside 
diameter and 50 inches in length between the end bulbs. The cathode 
consists of a pool of mercury contained in a flattened bulb that carries 
a short glass stem at its outer end. This stem contains the leading-in 
wire, which is submerged in the mercur>^, and during operation the 
current is carried by the mercury and the arc stream is in contact 
with the mercury surface. 

The current heats the mercury principally at the point of arc 
contact and the vapor here formed increases the pressure in the tube 
from 0.002 mm cold to about 1 mm during normal operation. The 
pool is so proportioned as to operate at a lower temperature than the 
rest of the tube and it acts as a condensing chamber to collect any 
excess vapor and thus aids in keeping the vapor of the arc stream in a 
superheated condition. This thermal balance normally keeps the 
tube free from deposits of mercury, but if the tube stands without 
operating for a considerable time mercury droplets will form along 
the tube, only to be dissipated when the tube is heated. 

The anode is made of soft sheet iron, stamped in a foHated design 
and then bent into a deep cup. The bulb containing the anode is 
but slightly larger than the tube. The anode is, of course, heated by 
the passage of current, but it does not reach a temperature of visible 
radiation. The arc contact is on the inside of the cup and it is spread 
out uniform^ over most of the area and does not concentrate into a 
hot spot or crater such as is formed on the anode of a carbon arc. 

The direct current tube has a single anode, while the alternating 
tube has two. The mercur^^ arc has a low resistance for the passage 
of an electron current from mercury to the anodes, but a very high 
resistance for the passage of current in the opposite direction. The 
alternating current lamp is therefore so wired and connected to an 
auto-transformer that the alternating current of the supply hnes is 
a unidirectional current through the tube. The rectification intro- 
duces wave distortions in the tube currents, and the total current is 
therefore not a series of sine waves, but is much more uniform. Due 
largely to the inductive action of the reactance coil that is in series 
with the lamp each cycle of current lasts more than half the time and 

Mercury A re — Benford 


there is considerable overlapping of the two current waves for the 
two anodes. This reduces the effective current to almost a constant 
flow and there is no visible alternating current flicker in the lamp. 

Fig. 1 T^'pe of unit used in tests. 




Fig. 2. Wiring diagram of alternating current unit. 

The lamp is started by an inductive kick from an inductance 
coil connected in series with a resistance coil and a mercury switch. 
Upon applying voltage a current of about an ampere flows through 
the switch and the resistance in series with it. AATien the switch 
automatically opens the resistance circuit a high inductive voltage 


Transactions of S.M.P.E., August 1927 

is applied between the cathode and a metal band around the stem of 
the cathode, and also over the length of the tube. This band does 
not make electrical connections with the inside of the tube, and part 
of the starting action is therefore of a static nature. The passage of 
a static spark from the surface of the mercury ionizes sufficient gas 
to make it a conductor that can be broken down by the relatively 
low applied tube voltage. To aid in the generation of the starting 
spark the cathode chamber is entirely covered outside with a metalUc 
paint that adds, by a condenser effect, to the size of the initial static 

•PLV )^. 







Fig. 3. Wiring diagram of direct current unit. 

The outer tube diameter on a group of 70 measured tubes was 
found to be 0.961 inches, with a wall thickness of 1 mm leaving a bore 
of 0.0885 inches, and an inner area of 138 square inches. This area 
determines the area of the arc stream, and it helps determine the 
average intrinsic brilliancy. 

2. Energy in the Visible Spectrum 
A determination of the distribution of energy in the visible 
spectrum of a mercury arc has been made by spectrophotometric 
methods. This type of test is ordinarily made with a radiometer, 
but the use of photometric methods is to be preferred in the present 
case on account of other tests made on the mercury arc with the same 

Mercury Arc — Benford 


An incandescent lamp was calibrated at a color temperature of 
2954°K and the energy distribution was computed from Planck's 
radiation formula. This lamp was used to illuminate a block of mag- 
nesium carbonate in front of one slit of the spectrophotometer, and 
the arc was placed directly in front of the other sHt. The width of 
the eye-slit was predetermined so that the light from any given spec- 
trum hne would fill only about one-third of the telescope sHt. By 


^ )00 
S^ SO 


^^ 50 























eo 40 (SO ffo ao 40 go so so ac go eo 

0400U 0.500U 0.G00/J 0.700U 


Fig. 4. Distribution of energy in visible spectrum. 

observing this precaution the reception of the entire energy of each 
of the mercury lines was insured. 

The spectrophotometer was equipped with a glass prism and 
consequently the dispersion of the spectrum was not uniform. The 
opening of the telescope was therefore computed in terms of the range 
of wave-length that would pass at any given setting, and from this 
computation the amount of emitted standard Hght was derived. 

There is apparently not much information available on intensities 
of the spectrum Hnes of mercury, and perhaps the reason for this is 
that most of the research workers using this arc have been interested 
in the positions and formations of the lines rather than their strength. 
Also, as used e^cperimentally the current density and tube tempera- 

370 Transactions of S.M.P.E., August 1927 

ture are apt to be highly variable and this would most likely disturb 
the relations between lines. 

Taking the entire energy in the spectrum between the Umits 
0.400 m.jjL and 0.700 m^a as 100%, the distribution with a 3.5 ampere 
tube was found to be 





25.33 per cent 





32.60 " " 




(blue green) 

0.14 " " 





30.90 " " 





11.04 " " 

If the above energies are reduced to light values by multiplying 
by the sensitivity curve of the eye the following light values are 

Violet 0.06 per cent 

Blue 1.37 " " 

Blue-green 0.17 " " 

Green 73.30 " " 

Yellow 25.10 " " 

In some of the published data, which are evidently intended to 

be largely diagramatic, the energy intensity of the pair of yellow lines 

is given as greater than any of the others. It seems to the writer that 

this distribution would give a light with a yellow green tone in place 

of the familiar blue-green. The above analysis with the green light 

greatly predominating seems to fit in better with the other data of 

the lamp, particularly the high camera speed of this light. 

3. Tube Brilliancy 

Illuminating engineers and others dealing professionally with 
light are always interested in the intrinsic brilliancy of Hght sources 
and doubtless the same interest exists, although in a different form, 
among the people working in motion picture studios. It is evident 
that mercury vapor has strongly marked radiation and absorption 
characteristics, and these factors determine the form of the distri- 
bution curve and the brilliancy of the tube as viewed from various 

An exploration for tube brilHancy at various angles shows the 
brilliancy to vary not more than 5 per cent for any angle within 70 
deg. of the normal. This is somewhat surprising, for the depth of 
gas in the line of sight at 70 deg. is three times the diameter of 
the tube, and if the vapor were perfectly transparent the brilliancy 

Mercury Arc — Benford 


should rise to about three times the brilHancy along the normal. 
Sorae prehminary research along this line has been done, but the 
work is rather involved because it must take account of both the 
radiating and absorbing properties of the vapor, the polarization 
factors and the interference of the glass tube. 

Fig. 5. Equipment for measuring tube brilliancy. 

In Fig. 6 the curve gives the brilliancy of the tube as viewed 
through a slot one quarter inch wide and having a length of 2 inches 
along the tube axis. Taking the normal brilhancy as unity, there is 
a decrease to 0.99 at 15 deg. from the normal, then a gradual rise to 
a maximum of 1.07 at 50 deg. At higher angles the brilhancy drops 
rapidly, being only 0.58 at 80 deg. An inspection of. the brilhancy 
curve shows why the photometric distribution so closely resembles 
that of a straight filament of uniform brilhancy at all angles. 

It has been found that there is an inverse relationship between 
tube diameter and brilhancy. A decrease of one per cent in tube 
diameter leads to about a one per cent increase in light output and 
tube brilhancy. 


Transactions of S.M.P.E., August 1927 

4- Depreciation Causes and Rates 

A mercury tube loses in quantity of emitted light as it becomes 
older in burning age, and some experimental work has been done to 
determine the causes and rates^of this phenomenon. It has been 
















/O 20 30 40 30 60 70 do 30 

Fig. 6. Brilliancy analysis of mercury tube, 

pretty clearly established that the blackening of the tube is the cause 
of the depreciation and not any change in the arc itself, nor in the 
glass of the tube. The tube ordinarily fails through loss of vacuum, 
and this is usually foreshadowed by the tube becoming a "hard 
starter." There is but little effect noticeable in the light output in 
the early stages of loss of vacuum, and the photometric output is not 
a sure indication of the probable life of the tube. This is in contrast 

Mercury Arc — Benford 


to the action in an incandescent lamp where a darkened bulb indicates 
a weakened filament and an increased probability of failure. The 
blackening agent in the mercury tube is iron from the anode, and as 
the wasting of the anode is not a factor in tube hfe there is but httle 
relation between the state of blackening of the tube and the proba- 
bility of failure. 

Fig. 7. Equipment for measuring transmission of tube. 

The particular nature of the tube blackening has been demon- 
strated in several ways, and the glass in the tube does not seem to be 
discolored or darkened to any particular degree. In Fig. 8 the curve 
gives the measured transmission through a tube of Ught originating 
outside the tube itself. A new tube that has been operated for only 
a few hours transmits about 80 per cent of the incident hght except 
near the mercury pool where a temporarj^ deposit of mercury reduced 
the transmission to about 70 per cent. This deposit forms while the 
tube is cold and the size of the mercury drops that form it gradually 
increases as the tube stands. The entire deposit disappears when the 
tube is operated long enough to become thoroughly warmed. It 


Transactions of S.M.P.E., August 1927 

should be here remarked that this same tube has an efficiency of 
transmission for Hght originating within the tube of over 95 per cent, 
and the low values here recorded are largely due to surface reflections, 
which in the case of an interior source do not greatly effect the effi- 

l^AVE LENQTH 0.570 


No. 8 

654 HOURS 

No.5Q NEN 


^1 I 1 I I 1 1 1^ 













4 10 16 ^^^834-40 4(3 

Fig. 8. Transmission factors of new and old tubes. 

ciency. The reflection loss in these experiments is about 20 per cent, 
or practically the entire loss shown for the center of a new tube. 

After a burning period of 834 hours the transmission curve of a 
certain direct current tube revealed a characteristic form that fur- 
nishes a clue to the cause of tube blackening. The section closest to 
the cathode showed a maximum transmission; then came a short 

Mercury Arc — Benford 


space of decreased transmission. From here to the center of the tube 
the transmission rose to 56 per cent and then decreased continuously 
to 39 per cent near the bulb of the anode. This minimum next to 



, &00L 












^/?/?< TURE 

















ISOO dOOO 2500 

SOOO J500 4W0 

Fig. 9. Depreciation characteristics of A.C. tube and unit. 











1500 iOOO E500 

SOOO 3500 4W0 

Fig. 10. Depreciation characteristics of D.C. tube and unit. 

the iron anode has been observed in every test and it is fair evidence 
of the guilt of the anode as the principal cause of depreciation. 

The depreciation rate of bare tubes under normal operating 
conditions is given by the upper curves of Figs. 9 and 10. The rate of 


Transactions of S.M.P.E., August 1927 

change becomes so small after several thousand hours as to require 
the most careful type of photometry to measure it accurately. Thus 
in the first 1000 hours of life the loss of Ught from one group of direct 
current tubes was observed to be slightly over 10 per cent, but the 
same tubes between burning ages of 3000 and 4000 hours depreciated 
only 2 per cent, and this lower rate seems to be maintained about 
constant for at least 10,000 hours. Some few lamps that have sur- 
vived to 40,000 and more hours warrant the belief that the deprecia- 














£000 3000 


Fig. 11. Average light output for any given life. 

tion rate continues to drop up to these exceptional ages where the 
ordinary risks of operation permit only a minute fraction of the tubes 
to survive. 

The rate of depreciation can be changed by altering the current 
through the tube. This is a result to be expected if blackening is a 
result of iron being vaporized off the anode. A series of tests made 
under overload conditions showed unmistakably that the deprecia- 
tion rate was increased, but there was no satisfactory data obtained 
on the total Ufe, or time of tube failure. The test was made on a 
circuit where the voltage fluctuated widely during certain hours of 
the day, and the average overload of 6 to 8 per cent in voltage is not 
a fair measure of the effective overload, as it is measured in tube 
blackening. The test did demonstrate, however, that the rate of 
depreciation rose with the voltage, but there is no clear evidence 
that the life of the tube is shortened by excess voltage or current. 

Mercury Arc — Benford 


3. Life Test Data 
To those mystics who beheve man to be a loquacious brother to 
the silent stone there should be comfort in the resemblance of the 
mortaHty rate of man and mercury tube. A group consisting initially 
of twenty-four tubes was tested for over 6000 hours and record was 
made of the survivors at various elapsed times. This group was too 
small to give precise data (assuming the possibiUty of such a thing) 



Fig. 12. 

3000 4W0 5000 GOOO 

Sample life probability data. 

but the characteristics noted below have been observed in other 
groups and the generality of the data can hardly be doubted. In 
laboratory tests the temptation to occasionally place the tube in the 
photometer is too great to be resisted, and hence we have no exact 
knowledge of how long a tube could be expected to burn if left 

During the first 1000 hours the tube mortality was high, amount- 
ing to 11 per cent of the total number, and 2500 hours were required 
to reduce the tubes a second 11 per cent, after which the mortality 
rate rose, and from the evidence of the test it would continue to rise 
for all longer periods. When the data are reduced to the probability 
of an "average" tube dying during any particular period we get the 
following figures. In the first 1000 hours the chance of failure is 


Transactions of S.M.P.E., August 1927 

0.11; during the second 1000 hours the chance is 0.03; during the 
third 1000 hours the chance rises to 0.05 and it is only after 3000 
hours that the chance of failure rises to the initial value of 0.11. 
After this the chance increases steadily to 0.20 during the period 








Fig. 13. Photometric distribution of A.C. tubes and units. 






Fig. 14. Photometric distribution of D.C. tubes and units. 

between 4000 and 5000 hours and 0.22 during the period between 
5000 and 6000 hours. 

The general resemblance between these rates and the mortaHty 
rates of humans will be recognized. During infancy the rate is high 
and falls to a minimum during the ages between 10 and l5 years. 
This corresponds to the period between 1200 and 2400 hours in the 
life of a tube, and both mortality curves rise continuously thereafter. 

There is at least one authentic case of a tube burning 40,000 
hours, but this is as unusual as the humans who are reported to have 

Mercury Arc — Benford 


have lived 150 years, and in both cases we are entitled to suspect 
that during the last third of their existence they were interesting 
solely on account of their age. 

Accurate hfe data are difficult to obtain. In shops and studios 
the failure of tubes is often occasioned b}^ accidental causes, and not 



























10 iO 30 40 50 60 70 80 30 100 110 120 130 140 


Fig. 15. A.C. volt-ampere cliaracteristics. 

to a failure of the seals, which seems to be the normal inherent cause 
of tube failure. 

6. Photometric Distrihution 

A new mercur}^ tube, that has not been blackened b}'- burning, 
radiates hght almost exactly as if it were a straight wire filament. 
In another place some of the reasons for this have been gone into in 
some detail, and for the present attention will be confined to the distri- 
bution changes that take place as the tube blackens, and to the effect 
of using a reflector. 

It was found that the deposit of black material that forms with 
age is much more dense along the top of the tubes, and in some cases 


Transactions of S.M.P.E., August 1927 

the top has been found to be very distinctly blackened with no visible 
trace of blackening along the bottom. Tubes vary among themselves, 
and instances have been found of nearly uniform distribution around 
the tubes. The general rule is however for the upper part of the tube 
to blacken at a much higher rate than the bottom and this leads to 

MERCURY i^RC (/\.C.) 


10 EO JO 40 JO GO 70 60 SO 100 110 £0 130 140 

Fig. 16. A.C. volt-watt characteristics, 

several secondary effects that are of importance both to the photo- 
metrist and to the engineer. 

The primary effect of the greater degree of blackening that takes 
place along the top of the tube is to reduce the upward intensity in 
a much greater degree than the downward intensity. In the particular 
case of a certain D. C. tube the loss at 4000 hours life was 18.6 per 
cent for the whole tube, but the loss directly downward was so small 
as to make its measurement a matter of some difficulty. The upward 
loss was 33 per cent, measured along a Une vertical to the tube. An 













^ X 


















Mercury Arc — Benford 


A. C. tube that lost 27 per cent in 4000 hours showed a loss along the 
downward normal of 10 per cent. It has been found that the relation 
between the upward loss and the downward loss is extremely variable 
in different tubes, as has been mentioned, and the reason for this 



i 10 

^ <bO 

^ 50 

1 /^ 













100 £00 dOO 400 -500 GOO 

Fig. 17. A.C. watt-light characteristics. 

variation is not clear, particularly when it appears in a group of lamps 
that have been operated uhder what seem to be nearly identical 

The reflecting surface used in these photometric tests was the 
usual equipment that is part of the unit. The curvature of the 
reflector is that of a circular cylinder, with the axis of the tube so 
placed as to secure a strong downward reflection such as would be 


Transactions of S.M.P.E., August 1927 

obtained with a light source at the one focus of an elUptical trough. 
The reflector comes below the bottom of the tube and all direct 
upward light is cut off. The net change is rather surprising, for the 
straight line distribution is changed into that from a luminous disk 
facing downward. This condition makes it easy to perform certain 


10 20 do 40 50 GO 70 do 30 100 I/O 120 130140 


Fig, 18. A.C. volt-Hght characteristics. 

computations of illumination which are much simpler when dealing 
with a symmetrical source. 

As the tube ages the resemblance to a disk increases and the 
distribution in any vertical plane becomes closely a circle. 

The efficiency of the reflector is influenced in a unique way by 
the selective blackening of the tube. In ordinary photometric parlance 
the efficiency of a reflector is the output of the lamp with the reflector 
divided by the output of the lamp alone. As a result of this usage the 

Mercury Arc — Benford 


efficiency of a reflector is influenced by its intrinsic reflecting power, 
its angular method of reflection and by the degree in which it encloses 
the lamp. As a general rule the efficiency of a reflector is increased 












VOLTA(iE Daop 

u IN be 


■i. ARC 


Fig. 19. Oscillograpli record of A.C. unit. 

384 Transactions of S.M.P.E., August 1927 

when the amount of light faUing upon it is decreased by withdrawing 
the lamp somewhat from the reflector. If, during ageing, the tube 
materially changes its distribution characteristic the result will be 
much the same as if the lamp were shifted outward with respect to 
the reflector. In the case of the mercury tube the percentage of 
Hght falling upon the reflector decreases continuously during the life 
of the tube and the initial reflector efficiency of 81.9 per cent has been 
found to increase to 83.5 per cent at 4000 hours tube life. This rise 
is believed to be unique as all other units depreciate at a rate that is 
greater than the bare lamp depreciation rate. 

7. Electrical Characteristics 

The low pressure mercury arc is a true arc in many of its electrical 
characteristics, but it differs in some respects on account of the con- 
fining effects of the glass tube. The usual arc between carbon elec- 
trodes is free to expand in diameter and change shape as the current 
grows, but in the case of an arc confined within glass walls the growth 
in diameter is limited and when this limiting action is well under 
way the arc alters its normal arc reactions and acquires an inherent 
stability. As an example, it has been found that the hght output is 
altered when the tube diameter is changed, and the arc is vastly 
more sensitive to ambient temperatures than the carbon arc which 
operates in a manner that seems totally independent of room tem- 
perature. This dependency is one of the reasons why precision photo- 
metry of the mercury arc is almost out of the question, but with 
proper attention to test conditions an agreement to within a few per 
cent can be expected in most of the photometric and electrical 
measurements that are customarily made. 

One of the unusual features of the alternating current lamp is 
the voltage characteristic as measured across the lamp. The voltage 
is, of course, composed of a positive and a negative wave during each 
cycle, but only one of these waves is effective in producing current, 
and the effective wave is altered greatly from the original sine for- 
mation. The technical difficulties of correctly measuring individual 
circuits are such that they are best avoided if accurate photometry 
is attempted, and for this reason the alternating current tubes were 
operated on an equivalent direct current during the photometric 
part of the investigation. 

The run-away nature of the arc is overcome by the confining 
action of the tube plus enough resistance in series with the arc to 

Mercury Arc — Benford 


give the combined resistance a positive coefficient so that an increase 
of current is accompanied by an increased total voltage drop. Be- 
cause of the almost unvarjdng active length of the arc the mercury 
lamp is normally more steady than an arc that is free to move and 
change its shape. 

The mercury lamp is somewhat unique among illuminants in 
having a rather definite point of maximum efficiency for any given 




K ^ 
























^Mp-'^- ' 1^-^ 



* "^ 





1 1 1 i 1 

/ ^ 3 ^ 5 G 7 6 S 10 1 1 IE 13 14 15 IG 

Fig. 20. Temperature characteristic at 25°C. 

design of tube. The practical side of this characteristic is that care 
should be taken to operate the lamps at rated electrical conditions. 
The starting characteristics of the direct current lamp are given 
in the next section, where the effects of ambient temperature are 

8. Tem'perature Effects 

The mercury arc is responsive to ambient temperature, and this 
fact is of particular importance when photometering the tubes. 
Care must be taken to have the tube in a stable thermal condition; 
otherwise, the photometric results may readily vary as much as 50 
per cent. In general, a slow progressive air temperature change is 


Transactions of S.M.P.E., August 1927 

not followed by any large response from the tube, although there 
are upper and lower temperature limits beyond which it is not wise 
to go. As an illustration of the reaction of the tube to ambient tem- 
perature the curves of Fig. 20 may be compared with those of Fig. 22 
for temperatures of 25°C and 66°C respectively. 














Tl IL 

Z>L=- J 


lL.rii L.i\n[U[\u 









<U / 


t IL 





1 1 1 1 1 1 

O I 2 3 ^ ^ G 7 8 S lO 1 1 1^ 13 14- 1^ IG 

Fig. 21. Temperature characteristic at 47 °C. 

These tests were made with a constant voltage of 110 volts 
across the terminals of the mechanism, which was separated from 
the tube, the latter being in a 2-meter sphere with a heater and fan 
for controlling the ambient temperature. The tube was not started 
until the ambient temperature had been held at the test level for 
15 minutes. 

At every test temperature between 25°C and 66°C the hght out- 
put was at a maximum during the first half minute of operation, and 
following this the light decreased sharply. At the lower temperatures 
there was a gradual recovery in output after from 2 to 5 minutes, 
but at the higher temperatures the output decreased steadily to a 
constant value at 8 or 10 minutes. These relations are plotted in Fig. 
23 where the shaded area represents the range of photometric values 

Mercury Arc — Benford 


obtained at ambient temperatures between 25°C and 66°C. At 
temperatures around 30°C a premature reading taken before the 
tube has had time to come to thermal equilibrium may yield values 
15 per cent high or 25 per cent low, depending upon the particular 
time of reading, but at 50°C and above, premature reading may be 
60 per cent or more above the readings taken when a stable condition 
is reached. As a result of these relations an attempt to photometer 





i 1 1 1 


, -A 


I 1 




1 or/rLnn lunL 








"~— . 


p~T — 1 — r — 1 — 




O I Z 3 ^ 5 G 1 6 3 10 1 1 IZ 13 14- 15 IG 



Fig. .22. 'Temperature characteristic at 66°C. 

mercury lamps under varying temperature conditions will often yield 
erratic test data, and if the temperature fluctuates rapidly as the tube 
is subjected to varying draughts of air the photometer reading will 
often pass beyong the range indicated in the diagram. The terminal 
voltage curves of Fig. 23 show two of the factors that contribute to 
forming lower and upper operating temperatures. The tube operating 
voltage at low temperature is abnormally high and this, in connection 
with a lower rate of ionization by the starting mechanism, leads to 
hard starting. At temperatures of 5°C and below the lamp is started 
with difficulty and this is a very real practical limit. The upper 
limit, due to high operating tube voltage, is not of much practical 
importance, being over 100°C and possibly as high at 125°C. These 


Transactions of S.M.P.E., August 1927 

temperatures would be encountered if the lamp were installed directly 
over a furnace, or the rolling table of a glass or steel mill. 

9. Reactions of the Eye 
The subject of the influence of the discontinuous spectrum of 
the mercury arc upon the human eye is, in certain circles, one that 



10 20 30 40 50 GO 70 

Fig. 23. Summary of temperature characteristics. 

is approached with caution, and the wise writer must always be 
prepared to make a strategic retreat, gracefully if possible, to less 
contentious ground. In the last 25 years many experiments have 
been made and many results obtained with but little agreement 
among them. Too often the results reflect the technique of the experi- 
ment rather than the characteristics of the light, but out of the mass 
of accumulated data certain facts seem to emerge. 

Perhaps the first fact is that mercury vapor Kght is not harmful, 
in spite of the terrible things it does to the most carefully prepared 

Mercury Arc — Benford 389 

complexion. This does not mean that by poor engineering the Hght 
may not be made harmful, for mispaced light of any character is 
dangerous, and the eye knows no exception. 

The second fact is that there is a distinction in the reaction of 
the eye to mercury light that is different than to any other light. 
The iris of the eye responds to levels of illumination, being large in 
diameter for low levels and small for high levels. It also responds to 
quick changes of illumination so that the diameter at any given 
moment is determined not only by the illumination of that moment 
but also by the previous illuminations for a number of minutes back. 
These changes are not so prominent when the illumination is from a 
mercury vapor lamp, and the difference in reaction is due to the fact 
that the controlling factor is the amount of infra-red (invisible) 
radiation present. These particular wave-lengths are weak or missing 
in the mercury spectrum and the iris remains wider open than would 
be the case for other light. This leads to three secondary reactions 
and has been the cause of endless dispute. 

The amount of light that enters the eye and the brightness of 
the image depend directly upon the area of the iris opening. Hence 
the mercury light for equal energy in the visible spectrum should 
produce brighter images on the retina than other illuminants. In 
photometry both types of light are received simultaneously and it 
would seem that the iris would be influenced by the infra-red of the 
standard lamp to take a diameter smaller than normal for the mercury 
light above. This leads to the belief that all measurements made 
between an incandescent standard and a mercury arc are conservative 
in value. 

The lens system of the human eye has two main optical defects 
that are common to all natural and artificial lenses. Different colors 
are refracted to different focal planes, the violet image lying in front 
of the principal image plane, and the red image lying behind it. Thus 
every image formed in the retina has a color fringe, but we have in 
some manner achieved the useful faculty of ignoring these colors, 
but even if ignored they still have an effect on acuity, or ability to 
distinguish details. In the mercury spectrum the red and orange 
parts are missing, and the spectrum length is reduced by over one- 
third. This reduces the color fringe and as a result the acuity is 
increased, often to a very useful extent. 

The outer parts of the lens are brought into action when the 
iris opens, and these parts are particularly defective in their chro- 

390 Transactions of S.M.P.E., August 1927 

matic focusing. Thus two opposing actions take place in comparing 
the mercury spectrum with a black body spectrum. The limited 
length of the visible mercury spectrum makes for achiity and the open 
iris tends to decrease acuity. The predominance of one or the other 
factor determines the relations between acuities it!nder the two types 
of spectra. 

In addition to the chromatic errors of the outer edge of the lens 
the curvature is also defective (spherical aberration), and the outer 
edge is inferior to the central parts in producing a clear image. Here 
again the discontinuous spectrum with a wide iris is at a disadvantage 
as compared with a continuous spectrum and a more restricted open- 

Even this brief outline of the factors that influence visibiUty 
show the complicated nature of the phenomena, and it is evident that 
the effects due to the fundamental differences between mercury arc 
and continuous spectrum lights is not easily evaluated. Some of the 
same relations exist in photography, but this is not the place to discuss 
this companion problem. 


Mr. Palmer: I should like to ask Mr. Benford a question about 
the constancy of light from a mercury arc, either A.C. or D.C. In 
making motion picture titles with a mercury arc, as the light source, 
the exposures become very short — about l/50th of a second, and it 
is claimed frequently that the irregular illumination of the titles on 
the screen is due to the fact that the light changes in value during 
short intervals, and I should like to know whether he has made any 
measurements or can give us any data. 

Mr. Benford: I am sorry to say I cannot answer the first 
question. I have never tried that. I do know that for ordinary 
photometry a lamp will be constant between ±5 per cent. In that 
respect it is surprisingly good when you are trying to get accurate 
data in a short time, but I don't know what would happen in shorter 

Mr. Mayer: Mr. Benford's comment on the efficiency increase 
of the lamp with the reflector fitting as the lamp blackens is a little 
hazy to me. 

Mr. Benford: In photometric circles we speak of the efficiency 
as the reflected light divided by the bare lamp light. If the lamp gives 
1000 lumens and only 800 lumens when put in a reflector, the efficiency 

Mercury Arc — Benford 391 

is 0.8. In the case of the mercury arc, due to the lamp giving off less 
and less light in the proportion upward, the reflector became less and 
less concerned with what was going on. 

Dr. Hickman: This deposit of iron which gets through; does it 
deposit on the walls in mirror form or is it black? I took it that it 
deposits on the tube. Is this practically black, non reflecting? 

Mr. Benford: It is practically black; it has little shine to it. 
Any light that hits it is a dead loss. 

Mr. L. a. Jones: I am very interested in Mr. Benford's remarks 
relative to the spectral distribution of energy in the radiation from 
the mercury lamp. We have not made any radiometric measurements 
but when necessary have used data taken from the literature of the 
subject. I have always felt that the value of energy for the yellow 
line was too high. This opinion is based on photographic photometric 
measurements. In actual practice the yellow line does not produce 
as great an effect as is indicated by the values commonly given. 

I presume that Mr. Benford also realizes that the distribution 
of energy varies somewhat with time. In using this light source for 
photographic purposes we frequently determine the effective "color 
temperature" of the lamp. Of course it is impossible to determine a 
true color temperature for a source of this type. We find that it 
requires 10 or 15 minutes for the lamp to reach an equilibrium from 
the standpoint of energy distribution, the "color" becoming effectively 
yellower as the lamp continues to burn. It appears that the in- 
tensity of the blue lines is relatively high at the instant of starting, 
gradually decreasing with respect to the yellow and green components 
nents as the lamp continues to burn. If the mercury lamp is used 
as a standard for photographic measurements we find it necessary 
to let it burn at least 10 or 15 minutes before making exposures. 

Mr. Benford: The lamp burned for half an hour before readings 
were taken, starting at one end of the spectrum, going to the other, 
and returning. The first and last readings on the same line checked 
satisfactorily, so that I felt I had reached stable thermal conditions. 
I do not know what the color composition would be short of that period 
of time. 

Mr. Crabtree: The D.C. mercury vapor lamp appears to 
visibly flicker at times. Perhaps Mr. Benford will explain what 
controls flickering. Also, are there any advantages in using an A.C. 
over a D.C. lamp? If so what are they? 

392 Transactions of S.M.P.E., August 1927 

Mr. Benford: I believe that if you are troubled with flicker, 
it may be from the service hnes. There is a small inherent flicker but 
with the proper voltage I can hardly conceive how this would be 
troublesome. With regard to A.C. and D.C., I believe the D.C. is 
inherently a little superior, on account of its steadiness. Most of 
our service lines are A.C at least a great number, and for that reason 
the A.C. has certain commercial advantages; but the fact that the 
mercury arc is a rectifying device, it is obvious that one should use 
D.C. when freedom from flicker is desired. I do not recall having seen 
visible flicker with a D.C. lamp. 

Mr. R. C. Hubbard: Bearing out what Mr. Benford has said, 
in our title department, we have found the flicker with tubes very 
noticeable. Changing to D.C. tubes has eliminated all noticeable 

Mr. Jenkins: I should like to ask if Mr. Benford has any data 
or can cite any source with regard to the time period — building up 
from no light to a maximum and also a period of light extinction. We 
want to project motion pictures by radio and must have a rapid 
valve and a constant light or a very rapidly changing light-source. 
As most of you know, the only motion pictures ever made by radio 
vision have used a Neon light-source, which we have been using for 
some time, but obviously it has its limitations. One can not make a 
very big picture till we get a stronger source. There are two ways 
open: one is to get a stronger light-source, which will vary without 
decrease in the spot, or get a valve that will control a constant source 
of light of high intensity. 

Mr. Benford : My measurements were made in termsof minutes. 
The quickest time of reading is 5 to 6 seconds, which is too long for 

Mr. Burnap : I think this question might be answered by saying 
that since this is a gas discharge it follows the same laws as all gas 
discharges. The change in light output for current change is instan- 
taneous, which is true of all gas discharges as far as can be measured. 

Mr. Crabtree : There is a matter of terminology of light sources 
of this nature. What term would be used to differentiate this from 
an incandescent lamp or filament? I brought this up in connection 
with a later paper by Dr. Engl, in which he uses the term "glow-light." 
^ Mr. Benford: I think when we refer to "glow," we refer to 
some of the discharges that surround the electrodes and have light 
zones in the tube. I think that is the ordinary conception. When you 

Mercury Arc — Benford 393 

have a continuous arc between the electrodes, you speak of it as an 
arc, whether in the tube or in the open. 

Mr. Porter: In co-operation with Mr. Foulks of the Cooper- 
Hewitt Company we have been making some interesting tests on 
mercury-arc, Neon, and incandescent lamps used for a\dation beacon 
purposes and have been finding some interesting things. We have 
been trying to find out which makes a more conspicuous beacon when 
viewed through fog. Due to the very great amount of energy of the 
mercury vapor lamp emitted in the yellow-green or blue-green end 
of the spectrum, to which the eye is very sensitive. We anticipated 
that mercury would make a good beacon observed at forty or fifty 
miles, but it is not so good as the Neon or the Mazda. We have been 
led to the conclusion that the Hght of the mercury lamp is absorbed 
very much more rapidly by slight haze, i. e., either absorbed or 
scattered, than light nearer the red end of the spectrum. I wonder 
if Mr. Benford has any measurements on the absorption of Hght. 
the air. 

Another interesting thing we have noticed is that a Hght of 
different color is quite valuable when viewed among many surround- 
ing lights. It is easier to pick it up even at 6 or 7 miles, and at close 
range the pinkish color of the neon and greenish color of the mercury 
are equally valuable with regard to color contrast to the city lights, 
but as you go out to greater distances, the Neon seems to lose its 
color contrast, whereas mercury retains its conspicuous green as far 
as you can see it. I should be interested to know if Mr. Benford has 
data along those fines. 

Mr. Benford : About ten years ago I measured the transmission 
of the atmosphere and found a surprising thing. Tests were made 
over a horizontal course of half a mile, and the weather was thick; it 
was distinctly misty. The transmission was about 57 per cent, which 
would correspond to poor seeing at night. I was very much surprised 
when I plotted the data to find that the transmission was almost 
identical with that of a dry atmosphere from a mountain top. I 
think I can draw a curve which will illustrate it. The transmission 
is 100 per cent. The transmission curve is very low in the violet and 
blue and rising to a maximum in the extreme red. Here is where the 
mercury arc falls down on this job. The energy is concentrated over 
the part of the low transmission. The red Neon has its energy con- 
centrated in that region where the transmission is high. This is for 
a half mile; if that test had been made over 3 or 4 miles with identical 

394 Transactions of S.M.P.E., August 1927 

conditions, the curves would be different, as at long range or in thick 
weather the Neon would be working on one part of the transmission 
curve and the mercury arc on another. 

Prof. Wall: Some years ago, about 1880, the main streets of 
London were illuminated with Wenham gas lamps, and some one 
thought it would be a great advantage to put in arc lamps. We 
had one day the worst London fog on record and all lights were 
switched on. It was found that the arc lights merely illuminated a 
small area, just close to the standards and in between was complete 
darkness. So the gas lamps had to be lighted with some considerable 
improvement. It is remarkable how, when looking down the length 
of a street in a fog, the lights get redder and redder the more distant 
they become, the blue and violet rays being completely absorbed. 
With regard to the emphasis laid on the yellow rays, is this not due 
to the fact that these, with the red and green lie nearer the maxi- 
mum of the visual luminosity curve? 

Mr. Benford : I think it is a matter of atmospheric transmission. 
When the air is thick, there is an enormous difference between trans- 
mission in the yellow and red. You might get a hundred times as 
much red as yellow, so that red is the only color that gets through 
at all. 

Mr. Briefer: I should like to ask Mr. Benford if he has made 
any measurements on the sensitivity of the mercury vapor arc lamp, 
to temperature changes. What I have in mind is, that when the lamp 
is in practical use in printing laboratories, drafts from open windows 
or ventilating fans may produce some condensation of the mercury 
vapor, with consequent diminution of light intensity and hence, such 
printing density changes as have been described in this discussion. 
Would it not be advisable to suggest to those who make use of this 
lamp, to shield it from cooling drafts and provide some means to 
keep the temperature surrounding the lamp reasonably constant. 

Mr. Benford: The lamp will react to drafts. If you suddenly 
change the temperature of the tube, you get all sorts of erratic results, 
as I found to my sorrow. If you allow the lamp to come to a stable 
condition it is almost constant; But while things are changing the 
arc is adjusting itself to some temperature equilibrium and you will 
get flicker. It is therefore, worth while to shield it. 

Mr. Briefer: Color blindness has nothing to do with visibihty 
of the nature mentioned by Mr. Wall. It is a fact that the red rays 
are much less scattered than the blue and intermediate. A yellow 

Mercury Arc — Benford 395 

light of low intensity should have better penetration in water fog 
than a blue light of high intensity. Probably the arc lights were placed 
at a high elevation to avoid the blinding intensity of the scattered 

Mr. Jenkins: It is unfortunate that my job is always the 
application of things in a new way, so that I am looking for these 
things. Why should we not use the red for photography under water? 
I should think the conclusions drawn here would lead to that. 

Mr. W. C. Hubbard : I do not think that Neon lamps have been 
available in sizes sufficiently large to do this under-sea photography, 
but the mercury vapor arc has been used successfully and is about to 
be used again using quartz or high pressure burners enclosed in 
pyrex cyHnders closed at each end and hung in numbers on iron frames 
range the pinkish color of the Neon and greenish color of the mercury 
are equally valuable with regard to color contrast ^ith the sur- 
rounding city Ughts. As you go out to greater distances, the Neon 
seems to lose its color contrast, whereas mercury retains its con- 
spicuous green as far as you can see it. I should be interested to 
know if Mr. Benford has data along those hnes. 

The lamps are started on the deck of the steamers and plunged over- 
board, submerged to various depths for lighting the bottom of the 
sea and for doing under-sea photography. This method was first used 
12 or 13 years ago. An expedition has been formed to go to the Islands 
of the Pacific to explore the coral fisheries. It would be interesting if 
some large Neon bulbs or lamps could be sent along and tried out 


December 15, 1926 

REGARDING the effects of the method of studio illumination 
^ upon the health of the actors and other studio employees, the 
subject is an intricate one which has many obscure ramifications. A 
complete statement of these conditions would necessarily involve an 
elaborate study from the standpoint of the Illuminating Engineer, 
the physiologist and a careful statistical medical investigation. 
There are, however, certain features which are so well known by the 
personal experience of everyone who has dealt with arc lamps that 
definite recommendations as to procedure in order to prevent any 
severe and immediately dangerous results in the use of arc lamps 
can be made at the present time. 

It has been the experience of workers with flame arcs and 
mercury arcs enclosed in quartz and other light sources which 
radiate a considerable amount of ultraviolet that severe and painful 
burns of the eye occur after a comparatively short exposure to these 
light sources. This ultraviolet burn when experienced in the motion 
picture studio has been called "Klieg eyes." This is an inflammation 
of the outer membranes of the eye ball. The trouble develops usually 
from 12 to 24 hours after exposure to the causative radiation. The 
condition is temporary and usually clears up completely within 4 to 
5 days. It is not an injury to the retina of the eye or to any of the 
interior elements of the eye as some people have supposed. The best 
work which has been done on this subject indicates that the outer 
coating of the eye, the cornea, the crj^staUine lens, and the humors 
absorb the ultraviolet fight so strongly that it is almost impossible 
for any of the radiation to reach the retina itself. 

Of ah of the papers which have been pubfished on this subject 
which one of the members of this Committee has been able to obtain, 
it seems to us that the one by F. H. Verhoef and Louis BeU* is by 
far the most complete and authoritative treatment. Their con- 
clusions are very positive that the commercial artificial fight sources 
can not, even under the most unfavorable conditions, cause any 

* The Pathological Effects of Radiation on the Eye, F. H. Verhoef and 
Louis Bell Proc. Amer. Acad. Art. Sci., 51, 1916 pp. 630-818. 

Same title, somewhat abridged, Trans. Ilium. Eng. Soc, 16, 625, 1921. 


Studio Lighting Report 397 

serious injury to the eyes if ordinan^ glass is interposed between the 
light sources and the eye. There is no doubt, however, that such 
sources as the white flame arc, high intensity arc, ordinary hard 
cored carbon arc, when used without any glass whatever, may cause 
the very painful although temporary condition known as "Klieg eyes." 

Ultraviolet radiation also produces an inflammation of the 
skin which later develops into a tanning that is practically identical 
with severe sunburn. It is also a well known fact that sunburn and 
tanning and other physiological action from natural sunhght is 
practically absent when the sun shines through ordinary window 
glass. Physiological experiments conducted with quartz mercury 
arcs and other sources of ultra\dolet radiation have indicated practi- 
cally no physiological action when the light from these sources was 
passed through ordinary types of glass and such physiological action 
could be obtained only when special glasses of extremely high ultra- 
violet transparency were used. 

One of the members of this committee, who is now the Illumi- 
nating Engineer of one of the largest motion picture studios, states 
that in his experience of 15 years around a motion picture studio he 
has never seen a single case where there was any permanent in jury- 
to the eyes of a worker from exposure to hght. "There were frequent 
cases of temporary eye burns before we began putting glass on the 
lamps, but this has practically disappeared now, and it is only 
occasionally when a man takes a chance in working near an open 
arc that we have trouble." 

From these well known facts the committee feels justified in 
stating that provided great care is used to enclose all arc lamps used 
for studio illumination with some sort of glassware there will be no 
danger that ultra\dolet burns will occur in the studio. There some- 
times exists an impression that provided the arc lamps are directed 
towards some portion of the set in which no action is to take place 
that ultra\dolet burns could not result. This, however, may be 
misleading as many objects would reflect enough ultraviolet to be 

In discussing the relation of studio lighting to health conditions 
in the motion picture industr>^, it must be borne in mind that direct 
sunhght such as is much used in motion picture photography has 
powerful physiological effects, and has been known to be fatal in 
some cases where persons unaccustomed to exposure to it have 
suddenly been subjected to long continued sun baths at the seashore. 

398 Transactions of S.M.P.E., August 1927 

in the desert, or on high snow-covered mountains. The Committee 
does not view this condition with alarm. The painful effects of a 
sudden overdose of direct sunlight are so well known to outdoor 
workers that the necessary advice of caution will doubtless be given 
to novices working with any responsible motion picture company. 
With very few exceptions immunity from any harmful effects due to 
even continuous exposure to direct sunlight is soon acquired. Short 
outdoor scenes are usually taken with no thought of harmful effects 
of sunshine and actors would naturally spend part of their time 
outdoors in the sunshine anyway. These rather obvious statements 
regarding sunshine are not included in this report not so much as 
warnings as they are to indicate the degree of severity or otherwise 
of the physiological effects of artificial studio illumination. These 
effects with glass enclosed arc lamps are much less than with direct 
outdoor sunhght. Persons who are not injured by direct outdoor 
sunlight will not be affected by glass enclosed arc hghts. 

It has been suspected for a long time that there are physiological 
effects of radiation other than the middle and far regions of the ultra- 
violet which are definitely known to cause sunburns, eye burns and 
the like. The ultraviolet just next to the visible portion of the 
spectrum, ordinary visible light, and high intensity infra-red radiation 
have been suspected or accused of undesirable effects. Such more or 
less obscure effects may possibly exist although at the present time 
there is no definite proof that they have any great action. Whatever 
effect is present is probably small and would not appear except under 
prolonged exposure. To detect any possible effects due to these 
radiations would require careful investigation by competent medical 
authorities. Such investigation and research might be desirable for 
the Motion Picture Producers and Distributors to have undertaken. 
If it is their desire to do so the Committee would be glad to cooperate 
in the selection of competent authorities. 

A word of caution can not be omitted as to the dangers of too 
great visual intensity if in direct line with the direction in which 
a person is required to look. Glaring lights of high intensity which 
blind the eyes temporarily are known to have deleterious effect upon 
the eyes of persons compelled to look at such lights continuously 
for a long time. It is suggested that hghts toward which an actor is 
compelled to look should at least be covered by a diffusing screen 
SO' that bright points of high intensity glare will not be in his field 
of vision. 

Studio Lighting Report 399 

The ordinary precaution of adequate illumination in all parts 
of the studio to prevent accidents should be provided. The Illumi- 
nating Engineering Society has developed a code of recommended 
lighting practice which can be utihzed if further information on 
this subject is needed. 


Pees. Cook: I suppose you all know that at our Briarcliffe 
meeting, Mr. Hays asked us to have an investigation made of the 
influence of studio lighting upon the actors and others exposed to it, 
and in response to the resolution of the Board of Governors, the 
Executive appointed a committee composed of Dr. Gage, Mr. L. A. 
Jones, and Mr. Palmer to investigate and report upon this. That 
report was handed to the Hays organization I think about January 
and was received by Mr. Hays with great appreciation and given a 
good deal of publicity. I have asked Dr. Gage to give you this 
morning the report which was prepared at that time for the Hays 

Me. Coffman: Pardon me for introducing a personal ex- 
perience, but I have suffered such painful effects from ultra-violet 
radiation and which were pecuhar to the medical profession that 
others maj^ benefit from my statements. A year ago last December I 
was making some films under conditions which demanded all the 
illumination I could get from the lighting line which came into the 
building. In order to increase this as much as possible, we used the 
arcs without diffusers, and it was necessar^^ for me to stand up in 
front of these arcs. Like most motion picture men, I became some- 
what afraid of the effects but after three days' work of that kind I 
left, and at that time felt nothing but the most extreme fatigue. I 
put it down to the hard work I had been doing, but my lower limbs 
began to swell and I suffered excruciating pain. I mentioned it to 
physicians, and when I spoke of the fights they smiled indulgently 
and pronounced it rheumatism. It got worse, and the pain later 
occurred in the arms as well as the legs; and along the paths of all 
the blood vessels in the legs the flesh began to turn red and got hard. 
There were no signs of infection, but within two weeks the lower 
Hmbs were as hard as stone, and it was impossible to move with 
anything fike normality although I had a tendency to keep moving. 
I found that in bed I suffered greater pain, and it was more difficult 
to^get up again, so that I dragged myself out of bed in the morning 

400 Transactions of S.M.P.E., August 1927 

and went town to the office with the aid of somebody or on all fours, 
but I felt better on my feet than I did before. That lasted about two 
and a half months, and I was being treated by the best physicians 
in New York. Most of the prescriptions had like effect. All color 
disappeared from my face, and there was no sign of pigment in the 
lips; people began to call me a dead man. Finally, Dr. Snook, of the 
Bell Telephone Laboratories, hearing about the case informed me that 
he had seen somewhat similar cases although none of them quite so 
severe and that the effect was caused by destruction of the red 
blood corpuscles. The symptoms were those of pernicious anemia 
as well as suffocation, because no oxygen was being disseminated to 
the parts of the body. The only thing was to let nature take its 
course, and I have been in good health ever since ; but some physicians 
were so completely uninformed as to effects of this sort that they 
actually prescribed ultra-violet treatment. I did not take their ad- 
vice; probably if I had I would not be here to tell the tale. You will 
excuse the remarks I make, for the experience has had such a tre- 
mendous influence on me that I feel impelled to warn everybody to 
avoid the ultra-violet. Incidentally, Dr. Snook said that one attack 
sensitizes to others, which I have found to be true and which seems 
to make it worth while recording the case, because whenever a slight 
dose of ultra-violet reaches me, I have the feeling of fatigue. 

Mr. L. a. Jones: The case reported by Mr. Coffman is indeed 
interesting. In going over the literature and discussing the subject 
with physicians, I have encountered a few cases of injury from over 
exposure to radiation which appear similar to Mr. Coffman's ex- 
perience. There seems to be some definite evidence that extreme 
over exposure to short wave radiation can cause injury to the blood 
corpuscles. I should like to inquire if there was any impairment of 

Mr. Coffman: Only temporarily, but no permanent impair- 
ment. One effect I did not mention, was complete destruction of all 
normal reflexes. Physicians do not believe I am insane, but until this 
last month they could not get any reflex, except in the eye. 

Mr. L. a. Jones: There is little doubt that an injury resulting 
from over exposure to ultra-violet does sensitize to subsequent 
exposure. I know of cases where an actual retinal burn due to over 
exposure to the direct radiation from the iron arc has been produced. 
Persons having suffered this injury are extremely sensitive to even 

Report of Papers Committee 401 

small amounts of ultra-violet radiation, this being e\ddenced usually 
by the production of head ache almost immediately upon exposure to 
even very low intensities of ultra-\dolet . I think there is little doubt 
that a serious injurj^ resulting from over exposure to ultra-\dolet may 
produce a very sensitive condition to subsequent exposure. 


PREPARATION of the program for the spring meeting was 
commenced in January 1927 and an advance program was cir- 
culated to all members three weeks in advance of the meeting. Only 
six papers were submitted voluntarily, two of which were from 
abroad. The fact that scientists in foreign countries are anxious to 
publish their researches in our Transactions is a good indication 
of the increasing prestige of our Society. It was necessar}^ for your 
Chairman to solicit most of the remaining papers and even to suggest 
the titles. It will probably always be necessarj^ to approach authors 
in this manner although under these circumstances it is possible to 
construct a suitable program rather than accept a variety of mis- 
cellaneous papers which may not necessarily be of topical interest. 

As a result of much pressure, about 75 per cent of authors 
have submitted manuscript in advance. Previemng of manuscripts 
is very necessary in order to eliminate any blatant advertizing matter, 
while it is possible to correct the manuscript so that it can be handed 
over to the Pubhcations Committee immediately after the meeting. 
Although 3 or 4 weeks must usually elapse after the meeting for 
correcting discussions, it is hoped that in this way some of the delay 
which has previously existed in issuing the Transactions will be 

For the first time in the history of the Society several papers have 
been secured from members in Hollywood. 

Your Chairman has taken the liberty of placing at the end of 
the program all papers which will not be presented personally by the 

At the suggestion of the Chairman of the Publicity Committee 
short abstracts have been prepared of all papers and will be available 
for representatives of the press. 

J. I. Crabtree, Chairman. C. E. Egeler. 

J. A. Ball. L. A. Jones. 


THE following items have received but one approval by the 
Society and should be ratified at this meeting. 

External Diameter of No. 1 Projection Lens. 

The external diameter of the barrel of a No. 1 projection lens shall be two 
and one thirty second of an inch (2-1/32 in.). (In metric measure 51.6 mm). 
Adopted Transactions No. 24. Discussion in Nos. 19 and 22. 


Mr. Mayer: Why can not the dimensions be expressed in 
decimals, or in both ways? Our proceedings should record both 
because it is customary for all societies to express everything in 

pRES. Cook: There is no reason, but since the first vote is on a 
fractional measurement, we could not in fairness change it at this 
time. The motion merely confirms the former vote on a dimension 
of 2% inch. 

Dr. Gage: This would involve changing over all dimensional 
standards. What I have done and am going to do, is to add the 
metric measurement. I think every manufacturer has a table showing 
the decimal equivalents of fractions. 

Mr. Richardson: I think that members not present at the time 
this was originally taken up will not know what it is all about. It 
is simply a difference of opinion of the lens makers. We must adopt 
the standard. We can not compel manufacturers to adopt it in 

Mr. McAuley: Have the lens makers been consulted? Very 
often tubing in fractional parts of an inch can not be readily obtained. 
If this has been taken up with them it is all right. 

Dr. Gage: The makers have certainly been consulted. One 
manufacturer is alreadj^ making lens barrels of this dimension, and 
we are asking the others to make them the same. 

Mr. John G. Jones: I beheve in fairness to the manufacturers, 
we should add plus and minus tolerances to the dimensions. 

- Mr. Griffin: I don't think it is necessary to specify tolerances. 
The method of mounting lenses in projectors, at present and in the 
future, is that they shall clamp in, so that tolerances are not required. 


Standards Committee Report 


Mr. Porter: Theoretically, we should have tolerances on all 
dimensions adopted. On the other hand, as manufacturing processes 
improve, those tolerances are liable to be cut down, and it seems to 
me that we lay ourselves open to prolonged and indefinite argument 
if we try to set tolerances on our figures. I think if we set standards 
and let the manufacturers set their own tolerances, we shall do better. 

Mr. Richardson: There is no tolerance necessary because the 
lens is mounted in a split ring. 

(The motion for adoption of the dimensional standard for the No. 1 
projection lens was passed). 

Dimensions of film splices 

At the last meeting it was adopted that film splices shall be made 
in accordance with the dimensions given in the figure (Fig. 1, p. 20, 
No, 27 Transactions) for laboratories and exchanges. This was held 
up at the request of Mr. Denison, but he agreed at the last meeting 
that this would be all right. 

(Motion passed to adopt above dimensions.) 

Perforation of positive film 
The dimensions of newly cut and perforated 16 and 28 mm posi- 
tive and negative, and 35 mm negative film have been approved 



i 1 

f \ 



V A 

2 MM. 

2.79 MM. 

0.465 ^^- 


3 MM. 


0.5 MM. 

Fig. 1. 
previously in accordance with the diagram printed on p. 8, No. 24 
Transactions. Approval was also given to the following perforation 
dimensions for 35 mm positive film (see Fig. 1). 

Either "Kodak" positive .110 inches (2.79 mm.)x .078 inches (1.98 mm.) 
with rounded corners as illustrated in the diagram Fig. I or the "Path4" positive 
perforation .118 inches (3 mm.) x. 0788 inches (2 mm.) with rounded ends and 
corners illustrated in Fig. 2, p. 9. No. 24 Transactions. 

We ask for a vote of second approval on this item. 

404 Transactions of S.M.P.E., August 1927 


Mr. Porter: Do I understand we are adopting both the ''Pathe" 
and ''Kodak"? 

Pres. Cook: Yes, and there is no change in the dimensions of 
those adopted many years ago, the only difference being in the shape 
of the corners. 

{Motion carried to adopt above dimensions.) 

Camera cranking speed 
The camera cranking speed of 60 feet per minute has received 
first approval in No. 24 Transactions as follows: and should be 
ratified at this meeting. 

A camera taking speed of 60 feet of standard film per minute with a 
minimum of 55 feet and a maximum of 65 feet should be used when normal action 
is desired, in connection with the Society of Motion Picture Engineers recom- 
mended (projection speed.) of 80 feet per minute. 


Mr. L. a. Jones: I should like to point out at this time that this 
question of taking speed will have to be reconsidered somewhat, if 
the reproduction of sound on the film come into practice. In re- 
producing music or speech it is necessary that the taking speed be 
the same as the projection speed. That is absolutely necessary for 
satisfactory reproduction of music, because of the pitch change. I 
think we should consider this because it is possible that film in the 
near future will carry sound records. 

Mr. Richardson: I have thought of that, but I think talking 
pictures will have to be dealt with by themselves. We can not apply 
the same rule to the regular motion picture and the talking picture. 

Pres. Cook: Gentlemen, there are two possibilities before us 
Many years ago we adopted 60 — somewhere around 1920 or 1921 or 
before that — and that was published for years in our book of Stand- 
ards. At Roscoe it was again taken up and discussed, and at that 
time it was repassed at 60 with a tolerance of 55-65. We can either 
vote to eliminate that tolerance of 55-65, and in that case we shall 
merely confirm the ancient standard of 60 without tolerance, or we 
can vote to sustain that tolerance. I think it might be as well to get 
the sense of the meeting as to which is preferable. 

Mr. Porter: I think the point that Mr. Jones has brought out 
is that with the increasing use of the recording of sound and pictures 

Standards Committee Report 405 

on the same film we will have to take cognizance of it. I see no reason 
why we could not do this adequately by adopting recommended 
practice of 60 feet per minute for cases where pictures only are recorded 
on the film, stating definitely that an exception is made for pictures 
and sound recorded simultaneously. 

Pees. Cook: I think we must consider that as new business. 
We are asking for the confirmation of that previously voted upon or 
the rescinding of it. 

Mr. Porter: I think we are at liberty to modify it and lay it 
over for 6 months. I consider this in the way of modifying the first 
adoption, which will hold it over for 6 months before final adoption. 
I think this is better than rescinding or adopting it at the present time. 

Dr. Gage: It is very evident with the speaking movies, that 
where the speech is on one edge of the film, we should have to change 
the dimensions of the aperture and have standards on speed and so 
on; but I think we should wait to find out what the manufacturers 
want as specifications for talking movies and then start out and draft 
a new set of specifications for such films, and let this matter come 
through for the kind of pictures we are talking about, which are not 
tied up with sound, thus clearing the decks of the present situation. 

Mr. Porter : I think the last recommendation is good, provided 
our adoption is so worded that it makes it specifically clear that this 
refers only to cases where pictures only are recorded on the film. 

Mr. Richardson: It seems to me that this is a case of too much 
delay. This was started at least 2 years ago, was laid over by two or 
three Conventions, and we have been bedeviled with it for several 
Conventions. I had well nigh forgotten about it. I believe before we 
adopt any camera speed, the Society of American Cinematographers 
should be consulted. 

Mr. Porter : They have been in great detail. 

Mr. L. a. Jones: May I ask, is this a standard or recommended 

Dr. Gage: Recommended practice. 

Mr. L. a. Jones: I move its adoption. 

{Motion carried to adopt above recommendations.) 

Intermittent Gear Ratio 
Listed among our Standards is the following which has received 
approval in the No. 10 Transactions at a time when a second rati- 
fication was not required. 

406 Transactions of S.M.P.E., August 1927 

The movement of the intermittent gear shall be expressed in degrees of 
rotation during which the pin of the driver is in contact with the slot of the driven 
gear. For example, a gear in which the pin is engaged with the slot for one-quarter 
of a revolution of the driver shall be called a 90-degree movement; that in which 
the pin is engaged with the slot for one-sixth revolution shall be called a 60-degree 
movement, etc. 

This is evidently Nomenclature and we ask that the rule of 
double approval of all Standards and Nomenclature be made unani- 
mous by second approval of this definition and that it be listed under 

{Motion carried to adopt above recommendation.) 

Sprocket Dimensions 
In the No. 27 Transactions is printed a report by Mr. J. G. Jones 
on the dimensions of sprocket wheels for projectors. The method of 
arriving at this standardization of sprocket dimensions, proposed by 
Mr. Jones, has I believe the approval of the Society. There has been 
raised an objection to the dimensions which Mr. Jones proposed for 
the take-up sprocket which is a hold-back sprocket. In the design of 
this sprocket it was assumed that if it is of such size that it corresponds 
to a film having a shrinkage of 2.92 per cent that no injury will be 
done to new film having zero shrinkage provided, of course, other 
considerations such as tooth thickness treated in this recommendation 
be complied with. It has been pointed out, however, that when 
perfectly new film is used, the last tooth of the sprocket wheel holds 
back the film until it lets go and, when it does so, there is a sudden 
jump of the film to the tooth just preceding it. Thus the sprocket of 
the dimensions recommended would give the greatest smoothness of 
action to film shrunk to 2.92 per cent but allows slipping from tooth 
tooth in the case of new film. This slipping action for new film was 
not assumed to be in the least injurious. It has been pointed out, 
however, that the standard tension of the wind-up which is 16 ounces 
on the periphery of a 10 in. reel is perhaps five times that amount 
or five pounds when a new reel is started and the film is wound near 
the hub. This jumping action on the new unshrunken film when used 
on a hold-back sprocket adjusted for the maximum 2.92 per cent 
shrinkage is highly injurious and moreover does the greatest damage 
to new film which is presumably both more valuable and is tenderer 
than old film. 

Standards Committee Report 


As a result of this the Committee in proposing a new dimensional 
standard has followed the general plan suggested by Mr. Jones, 
namely : 

The take-up sprocket which is a hold-back sprocket on a motion picture 
projector should be designed to have the same pitch as the perforations on film 
which has shrunk to the maximum amount occurring in films of commercially 
useful condition as suppUed by exchanges. The feed and intermittent sprocket 
are to have a pitch equal to that of the sprocket holes in newly finished film. 


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Sprocket dimensions proposed by Society of Motion Picture Engineers 

Intermittent sprocket with base diameter of 0.9452 in. (24.01 mm.) has same 
tooth pitch as the perforations of freshly processed film shrunk 0.13 per cent. 
Sprocket holes in theoretical contact with four teeth from A to B; i.e., the best 
running condition is for new film. 

Take-up sprocket which is a hold-back sprocket with a base diameter of 
0.9321 in. (23.67 mm.) is smaller and the tooth pitch is less than the perforations 
of newly processed film. There will be a slight clearance at the back of tooth C, 
also clearance between front of tooth C and all other teeth except the last tooth 
D which holds the film against the rewind tension. As the film leaves sprocket D, 
it will sUp forward off this tooth until the slight clearance between the sprocket 
and the next tooth is taken up. If the take-up sprocket is too small the slipping 
from tooth to tooth is excessive and particularly damaging to new film. 


Transactions of S.M.P.E., August 1927 

CHfi/fT B 
C.a.» DcfT., C Ku,.,n ft^/ft. 


Sprocket dimensions proposed by Society of Motion Picture Engineers 
with both English and metric dimensions 

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Sprocket dimensions proposed by Society of Motion Picture Engineers 

Standards Committee Report 


Film shrunk 0.75 per cent representing average film met with in service. 
Perforation pitch is sHghtly less than intermittent sprocket tooth pitch. The 
film is engaged by the last tooth B leaving a sUght clearance at the other teeth. 
As film comes off tooth B, it is engaged by the next tooth. Motion of film is aided 
by the snubbing action between the film and the base diameter of the sprocket. 

Film is held against rewind pull by the last tooth D of the take-up sprocket. 
There is increased clearance at the back of tooth C, hence no interference at the 
entering tooth. Compared to new film there is decreased shpping from tooth to 
tooth due to rewind pull. 

Film shrunk 1.5 per cent representing oldest commercially useful film. 
Intermittent sprocket moves the film by the leaving tooth B. No interference by 
the back of the entering tooth A occurs until the film is shrunk 2.92 per cent. 

Take-up sprocket has same tooth pitch as film perforations; i.e., the theo- 
retically perfect running condition six teeth are engaged. If film is shrunk more 
than 1.5 per cent interference will occur at the entering tooth C and the sprocket 
holes will be torn. 

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055 TOOTH 

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Sprocket dimensions proposed by the Paris Congress 

Intermittent and take-up sprockets both have the same base diameter, 
0.9390 in. (23.85 mm.). The tooth pitch is that of the perforation pitch of film 
shrunk 0.78 per cent. 

Film is shrunk 0.13 per cent. Entering tooth A of the intermittent sprocket 
engages the film perforation. When the next tooth engages film it pushes the film 
forward out of engagement with forward teeth. If tension is too great or film soft 
as in the case of new film the sprocket hole is Hkely to tear instead of pushing the 
film forward. This condition is to be avoided as it causes damage. 


Transactions of S.M.P.E., August 1927 

Take-up sprocket holds film against rewind tension by leaving tooth D 
and allows clearance to entering tooth C. This condition holds until film is shrunk 
0.78 per cent. 

ecpecsc/^Ts a condition witm film shbunkcn t 
euNNiNO ON speocKtTs with dimensions as 







Sprocket dimensions proposed by Paris Congress 

Tooth pitch same as perforation pitch of film shrunk 0.78 per cent. 

Film shrunk 1.5 per cent; i.e., old film. 

Intermittent sprocket engages film at leaving tooth B leaving clearance at 
entering tooth A. This good running condition occurs at 0.78 per cent shrinkage 
and holds until film has shrunk 2.89 per cent. 

Take-up sprocket engages film at entering tooth C. When next tooth E 
engages film, either (1) film is pushed forward, (2) film chmbs sprocket tooth or 
(3) perforation is torn. This condition occurs at 0.78 per cent shrinkage and is 
more aggravated the greater the shrinkage. 

The Committee finds that the maximum shrinkage of useful 
film is 1.5 per cent and recommends a take-up sprocket designed 
accordingly. The shrinkage of newly processed film for which the 
feed and intermittent are designed is 0.13 per cent. These latter 
sprockets as has already been shown will accommodate film shrunk 
as much as 2.92 per cent without damage. Dimensions of sprockets 
to produce these results are illustrated in Charts A, B, and C. The 
essential dimensions are: 

For take-up Base diameter 0.9321 in. (23.67 mm.) 

Sprocket Tooth 0.050 in. (1.26 mm.) 

Standards Committee Report 411 

For feed and 

intermittent Base diameter 0.9452 in. (24.01 mm.) 

Tooth 0.050 in. (1.26 mm). 

{Motion carried to adopt above recommendations) 

Ratio of Height to Width of Picture 
In the No. 18 Transactions it was voted as recommended 

practice that : 

The existing ratio of three to four between height and width of pictures 

when introducing any new size of film should be retained. 


Mr. Crabtree: This brings up the matter of pictures projected 
on a very wide screen. I suppose we should have to make other 
recommendations later on those apertures. 

Pres. Cook: That would be similar to the music films. I may 
say for the benefit of the Society that Dr. Gage and I have met the 
assistant to the secretary of the Standards Society, who explained 
that any standards adopted by the American Engineering Standards 
are always subject to revision, and they have a tremendous amount 
of this in other branches. The procedure is much simpler to revise 
than to get it adopted in the first place, so that we are not taking an 
irrevocable step in adopting any standard. 

{Motion carried to adopt above recommendation.) 

Camera and Printer Aperture Sizes 
In the No. 19 Transactions it was voted as recommended 
practice that : 

The camera aperture should be of such dimensions in relation to the pro- 
jector aperture that a picture with black borders inside the projector aperture 
shall be projected. 

In the No. 24 Transactions for the Roscoe meeting of Oct. 
5-8, 1925, p. 11, is found the following: 

In regard to camera and printer apertures, your committee believes it to be 
consensus of opinion in the Society that the black border is desirable. To obtain 
it we recommend the following aperture sizes: 
* Camera 0.700 in. high x 0.925 in. wide; 0.035 in. radius corner 

Printer: 0.757 in. high x 1.000 in. wide; 3/64 in. radius corner 

* Combination adopted as standard by the Incorporated Association of 
Kinematograph Manufacturers, Ltd. 

412 Transactions of S.M.P.E., August 1927 

Projector: (already standardized as 0.725 in. highx 0.950 in. wide; square 

The camera aperture corners may be either square or rounded, but the 
projector aperture corners must be square. 

Page 12. Motion passed to adopt above dimensions. 

It is evident that the Society seriously considered standardizing 
on the black border. However the size of projector aperture in con- 
tinuous use by all American manufacturers since 1911 and the present 
official standard of the Society of Motion Picture Engineers is 0.6795 
X 0.9060 inches. In the discussion of this proposed standard it was 
pointed out that it would be necessary to change the dimensions of 
the projector aperture. This has never been done and inasmuch as 
the above quotation states that the projector aperture is "(already 
standardized as 0.725x0.950 in. wide; square corners)" it does not ap- 
pear in the Transactions that the Society ever really intended chang- 
ing the dimensions of the projector aperture but it merely assumed 
that the dimensions, 0.725x0.950 in., was the standard it had already 
adopted. As a matter of fact the dimensions given for camera, printer 
and projector are the dimensions adopted by certain British manufact- 
urers the Incorporated Association of Kinematograph Manufacturers, 
and will give a black border. When, however, the same camera and 
printer aperture are used with the present standard projector aperture 
of 0.9060x0.6795, no border is visible. However, other dimensions of 
camera and printer aperture would give the same result; i.e., no 
border with the present small American standard projector aperture 
and black border with the larger British aperture. 

In order to put into dimensional standard form the requisites 
for possible projection of black borders, the Committee recommends 
the adoption of alternate aperture dimensions. The adoption or re- 
jection of these dimensions at the present meeting is a prerequisite 
for submission of our standards to the Engineering Standards Com- 

The dimensions suggested by the Committee are as follows : 

Dimensions of Projector Aperture. 

For the projection of pictures bounded by the image of the 
projector aperture, the projector aperture for standard film shall be 
sixty-seven hundred and ninety-five ten thousandths (0.6795 in.) of 
^an inch (17.26 mm.) high by ninety hundred and sixty ten thousandths 
0(.9060) of an inch (23.01 mm.) wide. 

Standards Committee Report 413 

(This is the present standard.) 

For the projection of pictures with photographically produced 
black borders secured by the use of the standard size camera and 
printer apertures, the projector aperture shall be seven hundred 
twenty-five thousandths (0.725) inches (18.42 mm.) high by nine 
hundred fifty thousandths (0.950) inches (24.13 mm.) wide with 
square corners. 

(This is the British Standard suggested as an alternate Standard.) 

The following should receive second approval if the black border 
is to be used. 
24 (Discussion printed in No. 18, letters from Mfg. No. 19 and No. 22) 

Camera and printer apertures shall be as follows: 
Camera 0.700 in. (17.78 mm.) high x 0.925 in. (23.5 mm.) wide; 0.35 in. 

(0.89 mm.) radius corners 
Printer 0.757 in. (19.23 mm.) high x 1.00 in. (25.4 mm.) wide; 3/64 in. (1.2 mm.) 

radius comers 


Dr. Gage: Consider what the adoption of the British aperture 
sizes might mean. Suppose that all pictures, taken by the producers 
after a certain time, were taken with this standard British aperture. 
We would then have films which will go through the present machines 
and look just as they do at present. When enough of these films were 
accumulated so that people would not get into trouble, it would be 
possible for the theaters to have the large apertures fitted into their 
projectors and to make whatever changes were required in the focus 
of the projector lenses used or possibly fixing up the screens so that 
they do not get into trouble with a painted black border, and as the 
theaters change over they will find that the films received from the 
exchange come out with the photographically produced black border. 
I would like to have the Society do something fairly definite about 
this at the present time, so that all matters will be straightened up so 
that we can deal with the AmericanEngineering Standards Committee 
in a way which will be dignified and have some weight, and which 
will not be likely to be too easity upset. 

Mr. Coffman: Is the Society quite sure of its psychological 
grounds on this? As I understand it, the apparent object is to com- 
pensate for variations in the intermittent sprockets of the camera or 
projector. At any rate, if there is a variation on the screen because 
of inaccuracies in the sprockets, if the projector aperture is larger 
than that of the camera, you will have a large bright field moving 

414 Transactions of S.M.P.E., August 1927 

against a small dark one. In other words, you will have variations 
which should be more apparent than the motion of the field within a 
fixed frame. 

Mr. Richardson: The idea was this: We have been projecting 
the picture a couple of inches over on the black border of the screen 
to hide the effect when the picture moves in the stationary aperture. 
The idea of this is that the opening will move with the picture; that 
is, the picture will not move with relation to the visible opening on 
the screen. 

Mr. John G. Jones: For Mr. Coffman's information: We have 
had a film made and demonstrated before the Society on two oc- 
casions and the consensus of opinion was that the black border picture 
appeared more steady. 

Mr. Townsend: The projection was not as practised in theaters. 
There was no permanent black border. It was projected on an open 
screen. While I have no authority to represent more than one theater, 
I want to go on record as being very much opposed to that practice. 
Distortion in the theaters is still present, and I predict that it will be 
there for a number of years to come, and when you put that black 
border in, you bring back the distortion and compel the theater to 
put the black border in further or use new lenses, which cost from 
S50 to SlOO apiece. 

Mr. Griffin: I think Mr. Townsend misunderstands the situa- 
tion. The size of the picture within the black border as we have 
recommended is a little larger than the picture projected by the 
standard aperture, and it was discussed at great length at onemeeting 
as to what would be best to do — let it ride and consider the error as 
there and not recognize it or recognize that it was there and not make 
another error. If angular distortion is present on the screen where the 
black border film is in use, it is expedient to use a standard aperture. 
Where they have an ideal condition, the black border serves two 
purposes; it serves to eliminate the idea in a person's mind of move- 
ment due to very tiny inaccuracies in the several machines through 
which the film passes before and during projection, and eliminates 
from view small particles of dirt that sometimes occur at the aperture. 
That is very bad, and inasmuch as the standard aperture can be used 
with that type of film, I do not see why it should not be adopted. 

Mr. John G. Jones : It seems that it has not been made clear that 
this Society is not forcing the use of the black border. It gives the 
conditions if and when people want to use it. 

Standards Committee Report 415 

Pees. Cook: For the benefit of the Society, it might be well to 
state whether this recommended practice is being followed by the 
makers of cameras in this country with which most of the pictures 
are being taken. Does any one know whether this corresponds with 
the camera aperture in general use? I would also point out that we 
have not very many members present who are as vitally interested in 
projection from an exhibitor's standpoint as Mr. Townsend, and 
possibly his being in the minority might not make it evident that the 
majority of exhibitors may take a different view from what we do 
from a theoretical standpoint. 

Mr. Crabtree: Has this been discussed with the American 
Society of Cinematographers? 

Mr. John G. Jones: The Standards Committee have worked 
out the dimensions for the apertures for the camera, printer, and 
projector, so as to project a black border. The dimensions arrived at 
were practically the same as those adopted by the Incorporated 
Association of Kinematograph Manufacturers, Ltd. Up to this time 
this matter has not been taken up with the American Society of 
Cinematographers . 

Mr. Porter: I should like to remind this body that this black 
border was demonstrated twice at two different meetings 6 months 
apart, and it was the opinion of each meeting that it was desirable. 
I understand Mr. Jones has the films here and will show them again 
if the Society wants to see them. 

Pres. Cook: The fact that we are favorably impressed with its 
desirability is hardly sufficient reason for its adoption, because there 
are many reasons why the present width of film might be considered 
too narrow for ideal results. The wider film might cause a better 
effect, but we should not think of increasing it, so that it seems to me 
that the fact that the picture has an obvious advantage made that 
way is hardly sufficient reason for its adoption, and it is my impression 
that most of those vitally concerned with the projection of these 
pictures will join Mr. Townsend in emphatic protest against the use 
of the black border. It is rather revolutionary to expect that the 
projectionists will adopt it. I think we should go rather slowly in the 
adoption of something quite so radical. 

Mr. Palmer: I think that Mr. Griffin has explained this in a 
very clear way which removes the objection that Mr. Townsend has. 
If you use the same aperture in the projector as is standard, you 
will not be bothered by the black border, and it is only the man who 

416 Transactions of S.M.P.E., August 1927 

wants the black border who needs to be considered. He can use a 
slightly larger aperture in his projector; it will be there if he wants it. 

Mr. Townsend: I did not understand that that part of it was 
that way, but in raising the objection I had given it considerable 
thought. There are things encountered by projectionists that people 
who look at the shows do not understand. With the present standard 
we have of a frame line between the sprockets there is a variation 
from it which causes slight mis-frames. I get more complaints from 
the management because of slight mis-frames than for any other one 
thing, because the operator running the show has several other things 
to watch. He is looking at the picture at a distance of 160-200 feet, 
and the slight line apparent in the theater is not always visible to him. 
The more leeway we give him the better the picture will look. If 
you have the black border, unless absolutely correct, it will be too 
low or too high. I don't want to take a lot of time holding up any- 
thing, but I want to make my objections clear. I did not understand 
it would come outside of the present aperture. 

Mr. Richardson: I do not think Mr. Townsend is quite as well 
inaposition to judge of thismatter because he looks on pro jectionfrom 
almost ideal conditions, whereas this is particularly designed to take 
care of theaters having poor film and as a consequence a lot of move- 
ment. Another thing: Four out of five theaters have distortion, and 
this is cured by filing the aperture. 

Mr. Griffin: I think Mr. Richardson does not quite under- 
stand. The size of the film picture is larger in all directions — vertically 
and laterally — than the standard aperture; therefore, when you file 
the edge of the aperture, you do not change the top and bottom. 

Mr. Richardson: You will on the sides, because you make it 
more narrow at the bottom. 

Mr. Griffin: The standard practice is to use a narrow aperture. 

Pres. Cook: Is it not a fact that the point brought up by Mr. 
Townsend that the objection of the occasional appearance of the 
frame line would be very much aggravated by the presence of the 
black border? If it is hard to eliminate errors so great that the frame 
line will show, it would seem to require constant attention to prevent 
the frame showing at the top or bottom. 

Mr. Griffin: I am inclined to agree with Mr. Townsend. 

Pres. Cook: The effect of a frame line is very unpleasant and 
this would come in constantly. 

Standards Committee Report 417 

Mr. Townsend: That is fundamentally my objection; it is 
almost instinctively so. 

Mr. Griffin : I move that it be laid over. 

(Motion passed to lay the recommendation on the table.) 

Mr. L. a. Jones : I suggest that the Chairman of the Committee 
take this up with the American Society of Cinematographers before 
the next meeting. 

Dr. Gage: The question has come up now as to what are we 
going to do with dimensional standards. We are in a jam in this case 
of projector aperture sizes. 

I should like to get the last two items off the list or get the pro- 
jector aperture off the list pending second adoption. 

Pres. Cook: Does the Chair understand that we have already 
adopted 0.6792 by 0.906? 

Dr. Gage: Yes. 

Pres. Cook: The object of the second one is to provide for the 
subsequent use of the black border which we have voted to lay on the 
table for future consideration. Would it be logical to adopt the 
projector aperture at this time without apparent justification for 
any change? 

{Motion made, seconded, and passed to lay the recommendation on 
the table.) 







Officers, Committees 421 

Presidential Address by W. B. Cook 423 

Report of Progress Committee, September, 1927 425 

Report of Standards and Nomenclature Committee 443 

An Exhibitors' Problems in 1927 by Eric T. Clarke 450 

Some Technical Aspects of the Movietone by Earl I. Sponable 458 

The Rendering of Tone Values in the Photographic Recording of Sound 

by Arthur C. Hardy 475 

Tachometers for Use in Motion Picture "Work by Nicholas M, Trapnell. 492 
Why Expert EJiowledge and High Grade Intelligence is Essential in the 

Projection Room by F. H. Richardson 500 

An Improved Condenser System for Motion Picture Projection by Lewis 

M. Townsend 512 

The Lubrication of Motion Picture Film by J. I. Crabtree and C. E. 

Ives 522 

An Experiment in the Development of Class Room Films by T. E. 

Finegan 545 

The Photographic Reflecting Power of Colored Objects by L. A. Jones. . 564 

The Tungsten Lamp Situation in the Studio by Peter Mole 582 

Factors which Affect the Contrast of a Lens Image in the Motion 

Picture Camera by Clifton Tuttle and H. E. White 591 

Animated Technical Drawing by J. A. Norling 601 

A Compact Motion Picture Densitometer by J. G. Capstaff and R. A. 

Purdy 607 

Advertisements 613 

Volume XI, Number SI 

MEETING OF SEPTEMBER 26, 27, 28, 29, 1927 

The Society of Motion Picture Engineers 
Its Aims and Accomplishments. 

fT^HE SOCIETY was founded in 1916, its purpose 
^Jy as expressed in its constitution being, ''advance- 
ment in the theory and practice of motion picture 
engineering and the alHed arts and sciences, the stand- 
ardization of the mechanisms and practices employed 
therein, and the maintenance of a high professional 
standing among its members/' 

The Society is composed of the best technical experts 
in the various research laboratories and other engineer- 
ing branches of the industry in the country, as well as 
executives in the manufacturing and producing ends of 
the business. The commercial interests also are repre- 
sented by associate membership in the Society. 

The Society holds two conventions a year, one in the 
spring and one in the fall, the meetings being generally 
of four days' duration each, and being held at various 
places. At these meetings papers are presented and dis- 
cussed on various phases of the industry, theoretical, 
technical, and practical. Demonstrations of new equip- 
ment and methods are also often given. A wide range 
of subjects is covered, and many of the authors are the 
highest authorities in their distinctive lines. 

The papers presented at the convention together with 
the full discussions are printed as Transactions after 
each meeting. These Transactions form the most com- 
plete technical library in existence of the motion picture 
industry. They are sent to each member of the Society 
and may be obtained by non-members at a very nom- 
inal sum. 

From the Hon. Secretary: 

L. C. Porter, 

Sth & Sussex Streets 

©CI B767661 / - 
'=' ' 'I — ir II "== 'I ^— =1' " ^ " "nl 








'' Volume XI, Number 31 / 

MEETING OF SEPTEMBER 26, 27, 28, 29, 1927 


l!=ir=i F=ii =n i II 1 1= i i===i f=s===i f=nnJil 




Copyright, 1928, by 
,' Society of 

]\![otion Picture Engineers 
\J New York, N. Y. 


Engineering Societies Building 
29 West 39th St., New York, N. Y. 

Papers or abstracts may be reprinted if credit is given to the Society of 
Motion Picture Engineers. 

The Society is not responsible for the statements of its individual members. 

FEB 20 1928 


H. P. Gage 

L. C. Porter 

WiLLARD B. Cook 

Past President 
L. A. Jones 

Board of Governors 
W. B. Cook 
J. I. Crabtree 
W. C. Hubbard 
L. A. JoxES 
J. C. Kroesen 
Max Mayer 
L. C. Porter 
F. H. Richardson 

F. A. Bexford 

W. C. Hubbard 

H. Griffin 

E. I. Sponable 



Standards and Nomenclature 
L. A. Jones Chairman 

D. MacKenzie 
L. T. Robinson 
R. J. Pomeroy 

J. H. McNabb 
R. S- Burnap 

L. A. Jones 

Papers and Publications 
J. I. Crabtree Chairman 
J. W. Coffman 

C. F. Bateholts 

H. T. Cowling 

K. C. D. Hickman Chairman 
J. W. Coffman 

B. J. Bach 

I. Gordon 

P. A. McGuire Chairman 

A. M. Beatty 
G. Edwards 

L. S. Cozzens 

P. A. McGuire 

L. S. Cozzens Chairman 
J. C. Kroesen 

J. H. Kurlander 

L. A. Jones 

Theater Lighting 
C. E. Egeler Chairman 
L. C. Porter 

J. R. Manheimer 


Fellow Members and Guests : 

IT GIVES me great pleasure to welcome you all to another annual 
convention of the Society, with such delightful surroundings and 
with such a promising program. As I look back over nearly ten years, 
during which I have been a member of the Society, I share with you 
in the pride and satisfaction in its growth, progress and accomplish- 

Most of the significant inventions and developments in our 
industry during the past decade have been announced or demon- 
strated at our conventions. Our Society has become the recognized 
authority for the reference of any questions pertaining to our industry 
and our Transactions have an international reputation as the 
greatest contribution to its technical literature. 

Our material and financial condition has kept pace with our 
scientific progress, so that the financial problems which formerly 
caused us much anxiety have been practically eliminated. 

In looking over the former executive addresses, one is strongly 
impressed with the number of recommended changes in the adminis- 
trative department of the Society. As a result of the changes which 
were made in accordance with the recommendations, the Society's 
business is now administered much more simply and I believe effec- 
tively by your Board of Governors than it was formerly conducted in 
open meeting with consequent confusion and loss of time during our 
conventions, which are now more profitably employed in the pre- 
sentation and discussion of the valuable papers which are contributed 
on these occasions. 

Probably few of the members who have not participated directly 
therein, realize the great amount of work which is undertaken and 
successfully accomplished by a few individuals who make up the com- 
mittees and members of the Board of Governors. 

Four years ago, we had 25 different committees functioning with 
more or less activity in our Society. Today, as much or perhaps more 
work is being accomplished by six committees. This of course means 
that the members of the present committees are devoting a larger 
proportion of their time and energy to the Society's business. This 
committee work has been facilitated to a considerable extent by the 
continuation on the various committees of men who have had several 


424 Transactions of S.M.P.E., Vol XI, No. 31, 1927 

years of experience in their respective capacities and have, therefore, 
acquired the abiUty to handle the work with a maximum of efficiency. 
It is only because of this familiarity with the duties as your executive 
that I felt justified in accepting the nomination for a third term as 
president, although two of my predecessors had each held a third term 
as your executive. 

About 80 firms or organizations have membership in the Society 
of Motion Picture Engineers, and we may with confidence assert 
that we are fairly representative of the technical part of the motion 
picture industry. As a result, there is hardly a department of the 
industry that is not benefited by the activities of our Society. How- 
ever, this is not as well known as it should be, and in spite of its 
importance, the Society is numerically small and comparatively 
unknown to a large number of people who are eligible for membership 
and who would be benefited thereby. 

We are not in urgent need of increased membership, but we wel- 
come new members who are in sympathy with the objects for which 
this Society was formed. The activities of the Society are wide in 
scope, and we are very liberal in our requirements for membership in 
our organization. With all this in mind, I earnestly request all mem- 
bers of our organization to do whatever they can to have the industry 
as a whole realize what we are doing. Speak a good word for the 
Society of Motion Picture Engineers whenever you can and assist 
in every possible way to show the entire industry why this organiza- 
tion should receive their full support. We wish the attendance at 
our meetings to be as large as possible, and we feel that every organi- 
zation that sends a representative to attend our conventions will be 
well repaid. 

In conclusion, let me extend my sincere appreciation to every 
member whose efforts have contributed to our success, to the organi- 
zations who have extended their support, and to the press and trade 
papers who have given us publicity. 

* Kodascope Libraries, Inc., New York, N. Y. 


September, 1927 Report of the Progress Committee 

ERHAPS the most striking occurrence since the last meeting 
of the Society, one which has affected the entire industry and 
which promises to leave a permanent impression, is the wave of econ- 
omy that struck the motion picture studios late last spring. Appear- 
ing first in the form of threatened salary cuts^ which met with furious 
opposition from those affected, it rebounded and swept over the 
managements and their production practices; Criticism of the waste- 
ful production methods in vogue was incited and various methods of 
reducing costs were discussed. At a meeting of the Academy of Mo- 
tion Picture Arts and Sciences a comprehensive agreement was 
reached, involving producers, writers, directors, actors, and all other 
studio workers, whereby it is expected that a noticeable decrease in 
studio costs will be evidenced.^ 

In connection with the problem of reducing production costs, 
several of the large studios have been experimenting with incan- 
descent lighting to replace arcs for general and special lighting effects. 
These experiments have met with marked success, as a result of which 
incandescent lamps are already extensively used.^ This method of 
lighting, comparatively new to the motion picture industry, promises 
not only to bring about a saving in operating costs of from 25 to 75% 
over the old,^-^ but also, when used with panchromatic film, gives 
better color rendition and eliminates the necessity for special make-up. 

Respectfully submitted, 

Carl E. Egeler, Chairman 
A. S. Howell J. I. Crabtree 

Wm. V. D. Kelly R. P. DeVault 


Rowland Rogers Kenneth Hickman 

Amateur Cinematography 
A new amateur motion picture camera of the upright type, called 
the Cine Nizo 16, with one film magazine above the other, may be 
either driven by its motor or cranked by hand. The cranking speed 
can be 16, 8, or 1 picture per second, depending upon the point of 
application of the crank. ^ 


426 Transactions of S.M.P.E., Vol. XI, No. 31, 1927 

Directions have been given for constructing a trick apparatus for 
the amateur to use in making animated drawings together with work- 
ing plans of the equipment, which includes a sturdy table, a support 
for the sketches, a staging for the camera, and suitable lighting 

An American manufacturer has made available a 16 mm. 
camera with the //1. 9 lens; thus it may be used for photography under 
adverse hght conditions.^ 


No new cameras of radically different design have been intro- 
duced recently, but some minor improvements have been noted which 
make them easier to use and applicable to more adverse conditions. 

A device of the finder type has been marketed which is said to 
ascertain correctly the field and angle of a picture to be taken, indi- 
cating what focal length lens to use, the exact proportion or dimen- 
sions of the subject to be photographed, and the photographic relation 
of colors and tones in the subject.^ 

The mechanism of a new gyroscopic camera tripod may be 
controlled with one hand. It is fitted with a locking arrangement 
which locks or releases instantaneously bj^ a half turn of a knob and 
which gives absolute rigidity.^ 

Announcement has been made of another improvement which 
may be adapted to any camera; a device which permits altering of 
focal length without losing any frames or interrupting the continuity 
of exposure.^ ° 

A new speed camera capable of taking 2600 pictures per second 
has been designed to study the exact character of flashes occurring in 
generators and other electrical machines. ^^ A new portable, spring- 
driven camera holds 200 feet of film and is capable of exposing 120 to 
150 feet at one winding. ^^ 

A patent has been issued on a hand-held motion picture camera 
having a curved gate.^^ 

Colored Motion Pictures 

Much patent activity is still evidenced in the field of colored 
motion picture photography. Some of the more important patents are 
briefly described below. 

Color record component images for additive or subtractive color 
cinematography may be produced by selective projection printing 

Progress in the Motion Picture Industry 427 

from a multicolor record image taken on film provided with a screen 
of lenticular or linear refracting elements. ^'^ Sensitive material for 
making these multicolor records is produced by rolling the film under 
the influence of heat with an engraved cylinder, which covers the rear 
surface of the support with minute refracting elements. ^^ Film thus 
embossed with microscopic linear refracting elements is employed in 
conjunction with a lens filter to produce objects in natural colors. 
A plate or cylinder whose surface is engraved with linear grooves num- 
bering 12 to 35 per millimeter and of any desired shape of cross section 
has been patented. ^^ 

A patent has been granted upon a method of color photography in 
which two films are employed having colors arranged so that the 
color of the action in front of the background should be a color not 
complementary to the other picture; that is, the action might be red, 
and the background blue.^'' 

Multicolor pictures visible by reflection or transmission may be 
obtained by forming a two layer screen, one layer having elements 
which are weakly colored compared with those in the second layer. 
The first layer may be a celluloid film, and the second a gelatin 
coating which is formed with screen elements by means of dyes which 
penetrate and color the film.^^ 

The optical density gradations in the highlight portions of 
dye-absorbent photographic film are made more gradual than those of 
the half tone portions in order to accurately reproduce the details of 
the scene. ^^ The densities in the shadow portions are made at least as 
great as those in the half tone portions.^" 

A new camera for color photography has four glass prisms of 
small angle slope to 90° apexes meeting concentrically at the axis of a 
large objective lens. With filters over the prism sections, four color 
separation negatives are obtained, and from these, positives, which 
may be combined by projection through a similar apparatus.^^ 

A description has been given of the two-color additive processes 
of Pilny, Wolff -Heide, and Friese-Greene. The Pilny process places 
the red and green filter images side by side in the space of one frame 
on 35 mm. film, the images being turned at right angles to their usual 
directions by a prism in the camera. Wolff-Heide and Friese-Greene 
take the two color records in alternation on the film, the negative 
being coated with an orange filter over alternate frames. The pictures 
on the positive are dyed red and green alternately by means of a 
protective coating of varnish. ^^ 

428 Transactions of S.M.P.E., Vol XI, No. 31, 1927 


A twelve year trial of education films has been made by the U. S. 
Department of Agriculture. During this period, over three hundred 
subjects were produced, of which two hundred and thirty are now in 
circulation. It has been concluded from this experience that educa- 
tional films are extremely effective and that the field contains 
enormous possibilities which may exceed those of the use of film for 
entertainment. 2^ It is said that too many tests of the educational 
value of motion pictures have been judged by the student's ability 
to pass certain examinations, and it is claimed that this is not a true 
measure of the worth of the films ; other tests have proved their value 
in broadening experience and stimulating interest.^* The motion 
picture may not always prove to be the most effective way of pre- 
senting ideas, but it has its own application which cannot be dupli- 
cated by any other means. In this connection it has been recom- 
mended that films be adapted to, but preferably subordinated to, the 
regular school curriculum. ^^ 

The educational application of pictures may fail if applied by 
enthusiasts with no regard to the special technic necessary. This 
problem has been studied and recommendations given. Accessibility 
and applicability of pictures, their availability at all times when 
needed, and a satisfactory means of projection are all important fac- 
tors which must be considered carefully.^^ 

Many schools will have their first taste of educational motion 
pictures this fall, and much valuable information and experience will 
undoubtedly be obtained during the next year. Pictures will be used 
in the Denver grade schools in the study of geography, health and 
hygiene, civics, fine and practical arts, and general science. 2'' 

A cinematographic program of education is being tentatively 
introduced into many English schools, but there is a scarcity of 
adequate film. Suggestions have been made relative to the future 
choice, preparations, and application of film in this connection. A 
report of a review of film made for the League of Nations Union and 
used for a series of history lessons in the upper classes of elementary 
schools favors the use of such film.^^ Films relating to agriculture, 
hj^giene, etc., have been produced in France and successfully applied 
to teaching.29 

Further progress is noted in the problem of education within the 
industry. The motion picture theater owners of the northwest have 
estabhshed a projection school at the Dun woody Institute at St. Paul.^° 

Progress in the Motion Picture Industry 429 

Films and Emulsions 

Film suitable for making duplicate negatives should have a 
higher resolving power than ordinary negative to keep graininess at a 
minimum, and should have a lower maximum contrast than motion 
picture positives to permit complete development . Such a film has been 
produced. ^^ Some additional experiments have been made to deter- 
mine the resolving power of photographic materials, and the results 
obtained show a large variation, depending upon the ratio, in a paral- 
lel line test object, of width of the line to the space. For the range 
investigated, a linear relationship exists between the resolving power 
and the logarithm of this ratio. ^- 

The causes of graininess in motion picture film and practical 
recommendations for reducing this graininess to a minimum were 
discussed in a paper presented before the last meeting of this societ3^ 
Graininess depends upon the density of the silver deposit, the nature 
of the emulsion, the exposure, the time which elapses between expo- 
sure and development, the nature of the developer, the degree of 
development, and the conditions during drying. ^^ x\n analysis has 
been made of the economic and photographic advantages of various 
reversal processes, and it is remarked that the reversal process gives 
finer grained images than the ordinary printing process. ^^ 

It is claimed that brightness in color and permanence in tone 
result from treating film, thoroughly washed after fixation, with a 
mordant bath of potassium ferricyanide, ammonium bichromate, and 
sulfuric acid in a water solution, and then applying a basic dye to the 
mordanted image. ^^ 

A chromate film of higher sensitivity may be produced by treat- 
ing unhardened gelatin-coated film with a special bichromate-ferri- 
cyanide-bromide solution. Films thus treated were said to have been 
printed at 113 to 240 meters per hour. However, attempts by others 
to apply the method have been unsuccessful.^^ 

Cellulose materials can be made more reactive toward acetylation 
or other esterification by pre-treatment with the vapors of lower fatty 
acids, such as acetic or formic acids or mixtures of these in an admix- 
ture of air or other indifferent gases or vapors.^" 

The difference between the reducing power of metoquinine and 
that of the mixture of methyl paraminophenol and hydroquinine are 
discussed in a reply to a paper of Hubl who disagreed with the 
opinions of Lumiere and Seyewetz on this subject.^^ 

430 Transactions of S.M.P.E., Vol. XI, No. 31, 1927 

Experiments have been made which show that the solubihties 
of the silver haHdes in hypo have been stated too high owing to the 
adoption of conditions favoring supersaturation. It is concluded that 
when the silver content of a 10% bath exceeds 0.6-0.7%, it becomes 
impossible to completely remove the silver salt by washing. ^^ 

The importance of halation on motion picture film has been 
discussed. Halation is of two kinds: diffusion halation, due to the 
diffusion of light by a turbid emulsion; and reflection halation, caused 
by light transmitted through the emulsion and then reflected by one 
or the other surfaces of the film base. Non-halation film solves the 
difficulty by giving non-reflecting surfaces on the film.^° 

The relation between the specular and the diffuse photographic 
densities were discussed in a recent paper. A formula was theoretically 
derived which correlates the so-called specular and diffuse density of a 
layer of light-scattering medium, such as a developed photographic 
film or plate. ^^ 

A patent has been issued on the manufacture of cellulose acetates 
or other esters of cellulose by a dry process. The cellulose employed as 
the starting material is pre-treated with organic carboxylic acids in 
the absence of solvents, and the reaction is performed by passing over 
or through the pretreated materials the vapors of acetic anhydride or 
other esterifying agent either alone or in admixture with air.^^ 

A British patent was granted on a substitute for celluloid as the 
support of the sensitive layer, produced by impregnating paper with a 
solution of artificial resin in alcohol. ^^ A French patent was issued 
on a process of embodying silk threads in the edges of motion picture 
film during manufacture.^^ 

Safety film must be as nearly chemically inert in relation to its 
sensitive coating as is nitrate base; its coefficient of expansion must 
not greatly exceed that of the nitrate base, and it must have uniform 
strength and retain its characteristics over a period of months.^^ 
The inflammability of nitrate film may be reduced by the introduction 
of cellulose phosphate; — cellulose can be satisfactorily nitrated by 
mixtures in which the sulfuric acid ordinarily employed is replaced by 
phosphoric acid.^^ 

In order to determine the strength of film splices, a series of tests 
were made on both fresh and old film with a number of different 
cements. Results of the tests were tabulated with the compositions of 
the various cements used.^^ 

Progress in the Motion Picture Industry 431 


Most modern movie palaces present a program which is a combin- 
ation of motion pictures and vaudeville or specialties, requiring effects 
of ''atmosphere" similar to those used in the legitimate theater. 
These are produced by so-called effect Hghting, of which there are 
three different divisions: the projection of animated scenic effects; of 
colored effects; and of simple masks, cutouts, and special lantern 
sUdes. A very comprehensive paper deahng with this subject was 
presented at the last meeting of the Society, in which a description 
was given of the various lighting effects together with the methods 
and apparatus used.^^ 

An organization knowm as the Academy of Motion Picture Arts 
and Sciences has been formed in Hollywood and is composed of di- 
rectors, writers, producers, actors, and technicians. It has the purpose 
of securing constructive cooperation among its members and the ad- 
vancement of the industry through the exchange of ideas. Scholar- 
ships will be given to assist persons working on improvements in the 
making of motion pictures, and a building is to be erected which will 
house a laboratory and a theater.^^ 

The eighth annual convention of the Motion Picture Theater 
Owners of America held in Columbus, Ohio, was characterized by a 
spirit of harmony and cooperation. Every effort was made to make 
the body truly representative of the industry, thus widening its scope 
and increasing its possibilities of service. ^^ 

A speed record was established in bringing to New York pictures 
of Lindbergh's reception at Washington. A special train equipped 
with a rolling laboratory in which the film was developed, printed, 
edited enroute, made the two hundred twenty six miles from Washing- 
ton to New York in one hundred eighty-seven minutes. The films 
were shown in a leading Broadway theater ten minutes after the 
train arrived in the station.^^ 

A new process has been patented whereby tragic and comic or any 
two pictures may be projected simultaneously, the spectators selecting 
for \dewing the one which interests them most. Two different colored 
images are produced on opposite sides of the film, which when looked 
at through suitable color screens permit viewing either image. ^^ 

A large steamship line now offers the attraction of motion pic- 
tures on shipboard. Portable apparatus has been installed, and the 
pictures are shown either on deck or in the saloon. The booth may be 
thrown overboard in case of a serious fire.^^ 

432 Transactions of S.M.P.E., Vol XI, No. 31, 1927 

A device patented in Germany is said to permit the taking of 
48,000 exposures per second. Such an apparatus will have a large 
field of application in scientific and experimental work.^^ 

A paper presented before a recent meeting of the Society calls 
attention to the many ways in which the National Bureau of Stand- 
ards may be of service to those working on technical motion picture 
problems. ^^ 

The handling of motion picture films under different climatic 
conditions, the transportation difficulties, and the manipulations and 
processing of film under arctic and tropical conditions have been dis- 
cussed in a recent paper. Detailed description is given of the equip- 
ment and manner of working.^^ 

Holland now has a motion picture studio located at Rotterdam 
said to be fully equippped to make large productions.^'^ Two Zeppelin 
hangars at Staaken, Germany, have been made over into modern 

The Eastman Kodak Company has inaugurated a four-minute 
reel series of pictures featuring well known actors and actresses. New 
subjects are to be issued monthly, so the amateur may build up a 
library of those he desires. ^^ 

France is making up films showing the history of its various prov- 
inces and part of each film is colored. Particular attention is being 
paid to the preservation of the film.^° 

A practical digest of the year's work in photography is given in an 

extensive resume containing 230 references, ^^ and another historical 

resume covers the development of the technic of motion picture pro- 
jection. ^^ 

Illuminants and Lighting 

While nothing fundamentally new has been introduced recently 
in the field of illuminants, constant progress is being toward the 
improvement of various types of light sources and in the improvement 
of light control equipment. 

Recent developments in high wattage incandescent lamps to- 
gether with the increasing adoption of panchromatic film is leading to 
a widespread use of incandescent lamps in the motion picture studio. ^^ 
Illuminating engineers from the east have been in the Los Angeles 
territory during the past summer cooperating with several of the 
large studios there in determining the correct types and wattages of 
lamps to be used and assisting in the selection and design of the proper 
light control equipment,^ '^* 

Progress in the Motion Picture Industry 433 

In a paper recently presented before the Society, the require- 
ments of studio hghting are discussed, and the advantages of 
incandescent Ughting are given with a cost analysis of the use of 
various types of light sources in conjunction with orthochromatic and 
panchromatic film. It is concluded that the desirable quality of the 
light and the convenient operating characteristics of incandescent 
lamps are large factors in determining whether these will be used to 
replace other types of light sources in lighting the motion picture 

A polygonal floodlighting mirror is described in a paper presented 
at the last meeting of the Society. The disadvantages are pointed out 
of refocusing the regular high intensity arc searchlight with the 
parabolic mirror to get a wider beam spread, and it is demonstrated 
that the use of a polygonal mirror is a more suitable arrangement. The 
method of computing the dimensions of the polygons is given as well 
as a photometric comparison of the two tj^pes of reflectors. ^^ 

A new fight source for Mazda projector lamps was described in 
another paper given at the last meeting of the Society. It is known as 
the coiled-coil filament source and consists of a single coil type of 
filament similar to that commonly used, coiled again to give a much 
higher degree of concentration. Its chief advantage is the higher 
screen illumination obtainable as a result of the smaller source size 
especially for lamps of the llo-volt class. It is at present applicable 
only to the lower wattage lamps, such as those used in the 16- 
millimeter film projector field. ^'^ 

A high intensity reflector arc lamp was recently demonstrated at 
Chicago. The practical problems involved in the construction of this 
equipment are the design of mechanical arrangements for the proper 
feeding of the carbons, regular burning of the crater, mirror location, 
and a reduction of the heat at the aperture. The problem of cooling is 
very important; this particular device accomplishes it by means of a 
motor driven fan which forces a stream of cool air past the film. To 
protect the glass mirror, a disc of heat-resisting glass is placed between 
it and the arc, and another air line from the fan directs a blast between 
this heat resisting glass and the mirror. ^^ Another reflector arc has 
been placed on the market. ^^ 

It is suggested that the Coolidge tube has possibilities as a pro- 
jection fight source. To employ it, the film might be backed with a 
mineral coating, or a suitable mineral surface could be arranged be- 
hind the gate to receive the bombardment of the electron stream. ^'^ 

434 Transactions of S.M.P.E., Vol XI, No. 31, 1927 

Laboratory Methods and Equipment 

It is necessary that motion picture film be cleaned at various 
stages in its progress from the laboratory to the theater and also after 
its use. A mixture of ammonia, water, and alcohol is satisfactory for 
cleaning the base side of the negative or positive film. To remove dust 
and finger markings from negatives before printing, wiping with 
silk plush moistened with pure carbon tetrachloride is recommended. 
The flexibility may be restored by passing it through a bath con- 
taining a mixture of water and alcohol. ^^ 

A pneumatic film squeegee has been developed for use in the 
laboratory to remove excess moisture after washing, before drying. A 
25% saving of time is effected through the use of the air squeegee 
and subsequent polishing of the film is unnecessary.''^ 

A method of impregnating wood with paraffin has greatly 
increased the value of wooden tanks for photographic solutions. 
Spruce so treated was found to withstand the action of acid and 
alkaline solutions with a minimum of absorption and consequent 
swelling. '^^ 

Trioxymethylene in the presence of sodium sulphite can be used 
to replace the alkali in the preparation of various phenolic developers. 
A fixing bath is recommended for photographic papers which employs 
trioxymethylene instead of alum as the hardening constituent. This 
is more stable than an acid-alum bath.'^^ 


An anastigmat lens said to be three times as fast as the //2.7 
has been placed on the market. It is claimed to give improved per- 
spective, the finest delineation and modeling, to be free from focal 
differences with the various stops, and to have complete correction 
for all colors of the spectrum. '^^ 

A patent has been granted on a projection lens having a short 
back focus, permitting the lens to be placed close to the gate. The 
focal length of the front component is equal to the sum of the focal 
length of the whole lens plus twice the back focal length. The com- 
ponents are separated by the focal length of the entire lens, which is 
the same as the focal length of the rear compartment.'''^ 

A seven-piece objective lens working at //I has been patented. 
Three of its seven elements are cemented together. ^^ 

Progress in the Motion Picture Industry 435 

New Applications 

X-ray motion pictures have been successfully made in England. 
The motion picture section of the Trade Commission in Paris reports 
that motion pictures of the hand, foot, and knee in motion, clearly 
showing bone movements, and of the chest showing the beating of the 
heart and movement of the ribs in the process of breathing were 
displayed before an educational body at the International Studio at 
Elstree, England."^ 

An apparatus for taking motion pictures of surgical operations 
has been patented which fulfills the conditions for asepsis. The camera 
is suspended from the ceiling and is controlled-by motors outside of the 
room; it takes a view that portrays the details and is said not to re- 
quire lighting harmful to the patient or operators.'^ 

Slow motion botanical studies ma}^ be made with a motion pic- 
ture camera having its exposure mechanism actuated by a clockwork 
motor, thus making single exposures at any predetermined intervals 
of a half minute to two hours. ^° 

The motion picture camera has been used to determine the melt- 
ing point and record the liquefaction of graphite in the electric 
furnace. ^^ 

Latest progress in the field of micro-cinematography is covered 
in a recent description of various devices used in this work. A camera 
having an auxiliary shutter between the lamp and the microscope is 
focussed from the rear through the film.^- 

A battery of four single exposure motion picture cameras were 
installed in a county court house to make photographic records. The 
cameras were suspended vertically over the records to be photo- 
graphed, and exposures were made by means of foot pedals; 40,000 
pages could be daily copied. ^^ The French have also made use of 
films in court. The details of a daring gem robbery were reconstructed 
and filmed, and the picture was shown for the benefit of the court- 
room at the trial. This is said to be the first time that motion pictures 
have been used in court for the application of justice. ^^ 


Some further experiments have been made to determine the effect 
of the motion picture upon the human eye. It has been reported that 
more eye fatigue was caused by 45 minutes' reading than by viewing 
black and white motion pictures for a period of one and a half hours. 

436 Transactions of S.M.P.E., Vol. XI, No. 31, 1927 

In fact, after a group had been reading for 45 minutes and showed a 
loss in acuity of vision, they immediately viewed a picture for an hour 
and a half and demonstrated a gain in acuity. Therefore, it is recom- 
mended that if your brain and eyes are tired, "go to the movies." 
These experiments indicated in some instances a greater loss in 
acuity after viewing black and white pictures than after viewing 
colored pictures. ^^ 


A new low-priced professional projector has been placed on the 
market in which is embodied everything in efficiency and construction 
that is found in more expensive tj^pes. Designed for a theater or hall 
of lOOO seats or less, it is equipped with a Mazda lamp and has been 
used to project a 16-foot picture at distances up to 135 feet.^^ 

A new gate mechanism has been developed for one of the leading 
makes of projectors now on the market. The chief feature of this new 
device is the fact that it is less affected by the high aperture tempera- 
tures of mirror and high intensity arc light sources. The mechanism 
consists of three heav}^ plates, a heavy grid kon plate facing the light 
source, another mounted upon and back of it which carries the gate 
latch, upper film shield and idler roller, and a steel plate wliich carries 
the tension shoes and springs.^" 

A patent has been granted on a motion picture projector having 
an adjustable optical sj^stem adapting it for use with either ordinary 
films or films having separated color component images requiring 
separate optical paths. ^^ Another patent covers a motion picture 
projector which has two motion heads alternately illuminated by one 
light source. It is claimed that substantially the whole of the light is 
utilized during its transference from one head to the other. ^^ 

An improved cinematograph projector has been described in 
which an epicychc gear drives the maltese cross and intermittent 
sprocket, thus increasing the operating speed. ^° 

A dissolving stereopticon using the reflector arc principle consists 
of an 8-inch parabolic mirror which intercepts the light from the 
usual horizontal carbon, directing it through two 5-inch diameter con- 
densers, giving two beams for a side-by-side slide projection. ^^ 

A careful studj^ has been made of the factors relating to the 
dimensions of sprockets for motion picture apparatus in view of their 
standardization, and the correct sprocket diameters for film? of var- 
ioiis shrinkages were determined.^- 

Progress in the Motion Picture Industry 437 


Approximately $1,500,000,000 are invested in the motion picture 
industry, Sl,250,000,000 of which are invested in theaters, the balance 
in studios and distributing offices. ^-^ 

Imports and exports of motion picture film of the United States, 
Germany, England, and France, have been given in a summary which 
covers the last three years. ^* A report of the United States Depart- 
ment of Commerce shows a decrease in exports of motion picture film 
for the year 1926.^^ The export of unexposed film from Germany to 
the United States decreased from 26,062,800 kilograms in 1925 to 
15,692,300 kilograms in 1926. Export of other films increased from 
58,500 kilograms to 100,600.96 

The South AmxCrican market strongly favors United States films, 
90% of the pictures shown there being made in the United States." 

A report has been made which gives the industry's income for 
1925. In this year, 5,376 amusement corporations and 314 motion 
picture producers filed returns with the Government showing their 
assets in cash, accounts receivable, notes receivable, inventory, 
fixed property and investments, "and their liabilities in accounts 
payable, notes pa^^able, bonded debt, and mortgages. ^^ 

A survey has been made of the producing organizations and of 
the distribution and exhibition conditions in Europe and England. ^^ 
It has been reported to the Department of Commerce that in metro- 
politan France 3,995 motion picture theaters are registered, 180 of 
which are in Paris. Twenty-four of the Parisian theaters have more 
than 1500 seats. ^°° There are approximately 9500 theaters in Central 
Europe, Spain, and Italy. Germany, the largest motion picture mar- 
ket in Europe, had at the beginning of 1926, 3878 theaters. In Ger- 
many, 206 producers made 246 pictures that year.^°^ Belgium has, 

according to another survey 1000 theaters, 100 of which are in 
Brussels. ^^2 

Australia has one picture house for each 5000 of population, ^°^ 
while 900,000,000 people in the Orient are served by 1600 theaters. 
Japanese producers make approximately 700 features yearly. ^^^ 

Stereoscopic Motion Pictures 

A large producing organization has acquired the rights to a 

process of making third dimension pictures, developed by two Swiss 

inventors. No auxiliary apparatus is required to project films made 

by this process; standard theater projectors are used, and the pictures 

438 Transactions of S.M.P.E., Vol. XI, No. 31, 1927 

are viewed with the unaided eye.^°^ A film has been completed which 
is said to have met all expectations. ^°^ 

A patent has been issued upon another means of stereoscopic 
projection which employs two screens placed at opposite ends of a hall. 
The spectators can see directly only one screen and are provided with 
a viewing means which enables them to register the two sets of images. ^°'^ 

It is said that a stereoscopic illusion is attained through the 
use of the so-called "magnascope." Another feature of this device is 
that a picture 30X49 feet in size may be projected. ^°^ 

A motion picture screen composed of small glass particles has 
been installed in a New York theater and is said to give an illusion of 
depth with ordinary projection. ^°^ 

In an amusement park in Berlin, still and motion pictures have 
been projected on a curtain of spray from jets of water, giving an 
illusion of relief .^^° 

Talking Motion Pictures 

A new device for projecting talking pictures is called the Fil- 
mophone. A selenium cell is used to convert the light to electrical 
energy; the film can register oscillations of a frequency of 10,000.^" 

The Photophone is to be sold direct to theaters. Concentration 
of effort will be directed upon music scores for accompanying films. 
Synchronized scores will be made for features from all companies who 
will cooperate to the extent of furnishing a print for screening. Thus, 
even the smallest of theaters may have excellent musical entertain- 
ment with their pictures. ^^^ 

Two other sound synchronization devices about to be made 
available are the Vocafilm^^^ and the Orchestraphone.. The Orchestra- 
phone is designed primarily for small theaters and was recently given a 
trial in a Chicago theater.^ ^^ 

The effect of the spreading of the image due to irradiation on the 
sound record in the case of talking films has been reported. ^'^ 

In Vitaphone productions, the synchronization of sound recording 
and picture taking is constantly checked by a stroboscopic apparatus 
employing a sector disc and a Neon tube. A loud speaker is also used 
in the recording room to check the quality of electrical "sound" 
fluctuations. ^^^ 

Trick Cinematography 
, An interesting paper was presented before the last meeting of 
the Society describing various methods of obtaining illusions in cine- 
matography. The different technical, artistic, and dramatic problems 

Progress in the Motion Picture Industry 439 

involved in the production of four different effects or scenes were 
discussed and a description given of the methods used J ^^ In another 
paper presented at this meeting a resume was given of various 
patents which have been issued on methods of trick photography.^^^ 

Fifteen methods of trick photography have been described to 
illustrate how the cinematographer analyzes motions in two or more 
directions. Reverse camera, glass work, double exposure, one picture 
turn, decreasing the taking speed, slow motion photography, stop 
camera and substitute, fade in and fade out, double printing, double 
exposure by use of mirrors, projection printing, and the use of mechan- 
ical devices are among the methods described. ^^^ 

A method of trick photography known as the Schuefftan combin- 
ation process has been patented. A mirror having the silver backing 
removed locally is placed in the field of the camera, and part of the 
scene painted in miniature is taken by reflection in the mirror. The 
images are made to blend into each other by vignetting the clear 
opening in the mirror. ^20,121, 122 'pj^jg process has proved useful for 
many kinds of motion picture work, including color cinematog- 
raphy. ^23 Further applications of the process have been enumerated. 
The relative sizes of objects can be changed by placing them at differ- 
ent distances. A collecting lens is used on the other side of the mirror 
to bring both objects into focus in the camera, and with a combina- 
tion of several mirrors the size of the vignetted exposure aperture 
hole may be varied during the action. ^^4 

Another new process has been described in which action taken 
on one location may be superimposed with complete naturalness on 
scenes which were made on another location. ^-^ 

Two other recent patents cover processes in which pictures are 
taken by the use of direct masks and masked reflectors in the field 
of view, ^26 ^^^ ^ method is employed in which silhouettes are thrown 
on a transparent background. ^^^ 

1 Moving Picture World, June 25, 1927, p. 559. Motion Picture News, 
June 24, 1927, p. 2433. Motion Pictures Today, July 2, 1927, p. 3. 

2 Motion Pictures Today, Aug. 2, 1927, p. 3. 

3 American Cinematographer, Aug. 1927, p. 22. 

4 Film Daily, July 2, 1927, Vol. XLI, 17, p. 1. 

5 Rabier, Filmtechnik, May 1, 1926, pp. 184-G. 

6 E. Palme, Filmtechnik, Nov. 10, 1926, pp. 537-40. 

7 The Cine Kodak News, June 1927. 

8 Motion Picture News, July 15, 1927, p. 144. 

9 Kinemat. Supp., Oct. 28, 1926, p. 95. 

440 Transactions of S.M.P.E., Vol XI, No. 31, 1927 

" Kinemat. Weekly, March 10, 1927, p. 69. 

11 Ed. Screen, April 1927, pp. 184-6. 

1^ Phot. J., January 1927, 57, p. 18. 

13 French Pat. 615089. 

1^ Soc. du. Films en Couleurs Keller-Dorian, British Pat. 263115. 

15 J. Audebert, Soc. du Films en Couleurs Keller-Dorian, British Pat. 

i« Soc. du Films en Couleurs Keller-Dorian, British Pat. 261363. 
1" C. D. Dunning, U. S. Pat. 1613163. 

18 L. Dufray, British Pat. 262386. 

19 E. A. Weaver, Technicolor M. P. Corp., British Pat. 263331. 

20 E. A. Weaver, Technicolor M. P. Corp., British Pat. 263650. 

21 A. B. Crow, Phot. J. 67, March 1927, p. 152. 

22 A. V. Schwertfuhrer, Filmtechnik, May 29, 1926, pp. 226-8. 

23 F. W. Perkins, Trans. S.M.P.E., No. 26, 1926, pp. 48-54. 

24 R. Gow, Ed. Screen, Feb. 1927, p. 71. 

25 J. N. Emery, Ed. Screen, May 1927, pp. 213-4, 247. 

26 J. E. Dransfield, Ed. Screen, March, April 1927, pp. 121-2, 150, pp. 165-8, 

27 Motion Pictures Today, Sept. 10, 1927, p. 3. 

28 R. Gow, Ed. Screen, Jan. 1927, p. 6. 

29 L. Alexandre, Cinemat. Franc., March 26, 1927, pp. 41-2. 

30 Moticn Pictures Today, June 11, 1927. 

31 J. G. Capstaff, M. W. Seymour, Trans. S.xM.P.E., No. 28, 1927, pp. 223-9. 
Amer. Cinematographer, Dec. 1926, pp. 9 et seq; Kinotechnik, 1926, pp. 

32 O. Sandvik, J. Opt. Soc. Amer., 14, Feb. 1927, p. 69. 

33 J. I. Crabtree, Trans. S.M.P.E., No. 29, 1927, pp. 77-92. 

34 L. Busch, Filmtechnik, Nov. 13, 1926, pp. 459-61. 

35 Bioscope Supp., Dec. 16, 1926. p. vi. 
3" Atelier, 33, October 1926, p. 116. 

37 H. Dreyfus, Brit. Pat. 263938, 263969. 

38 Bulletin de la Societe Franjaise de Photographic, November 1926, p. 312. 

39 B. J., Feb. 18, 25, 1927, pp. 91-3, 105-7. Kinotechnisches Jahrbuch, 1925- 
26, p. 114. 

40 Kinotechnik, June 10, 1926, pp. 290-2. 

4j L Silberstein, C. Tuttle, J. Opt. Soc. Amer., May 1927, pp. 365-73. 
Sc. Ind. Phot., June 1927, pp. 25-28. 

42 H. Dreyfus, Brit. Pat. 264937. 

43 V. Busch, Shoeller & F. Bausch, Brit. Pat. 260306. 

44 U. Diem-Bern et, French Pat. 617929. 

45 C. N. Bennet, Bioscope Supp., March 17, 1927, p. 15. 
« C. K. Keaus, F. B. Blechta, Chemical News, 134. 

47 Kinotechnik, Oct. 10, 1926, p. 488. 

48 J. H. Kurlander, Trans. S.M.P.E., No. 30, 1927, pp. 188-207. 

49 Motion Picture News, May 27, 1927, p. 2059. 

50 Motion Picture News, June 17, 1927, p. 2347. Motion Picture World, 
• ' June n, 1927, p. 397. 

61 Motion Picture News, June 24, 1927, p. 2414. 

Progress in the Motion Picture Industry 441 

=2 W. V. D. Kelley, D. Tronolone. V. S. pat. 1615283. 
53 W. Steinhauer, Filmtechnik, Dec. 25, 1925, pp. 372-4. 
^ Motion Picture News, Sept. 2, 1927, p. 699. 

55 G. K. Burgess, Trans. S.M.P.E., Xo. 26, 1926, pp. 61-9. 

56 R. J. Flaherty, Trans. S.M.P.E., Xo. 26, 1926, pp. 85-93. 
" Motion Pictures Today, Aug. 13, 1927, p. 8. 

58 R. Kuntze, Filmtechnik, April 3, 1926, pp. 174-5. 

59 Motion Pictures Today, June 4. 1927, p. 8. 
•^0 Motion Pictures Today, May 14, 1927, p. 8. 
El Amer. Ann. Phot. 1927, p. 179. 

62 Moving Picture World, March 26, 1927, pp. 329-30, 444-5. 

63 Paramount Studio Xews, Sept. 7, 1927, p. 4. 
^ Paramount Studio Xews, Sept. 7, 1927, p. 1. 

'5 E. W. Beggs, Trans. S.M.P.E., Xo. 26, 1926-, p. 94-106. 

66 Frank Benford, M. W. Pahner, Trans. S.M.P.E., Xo. 29, 1927, pp. 109-21. 

67 H. I. Wood, Trans. S.M.P.E., Xo. 29, 1927, pp. 56-60. 

68 Motion Picture Xews, July 1, 1927, p. 2526. 

69 Motion Picture Xews, April 1, 1927, p. 1152. 
"° Bioscope Supp., Xovemher 25, 1926, p. ix. 

71 J. I. Crabtree, H. C. Carlton, American Cinematographer, ^lay^ June 
1927, pp. 9-10, 20-3. 

72 J. I. Crabtree, C. E. Ives, Trans. S.M.P.E., Xo. 30, 1927, pp. 270-6; 
American Cinematographer, July 1927, p. 7. 

73 L. W. Eberhn, A. M. Burgess, Ind. Eng. Chem., January 1927, p. 87. 
7^ A. & L. Lumiere, A. Seyewetz, J. Suisse, Phot.. ^lay 7. 14, 1926, pp. 159- 

61, 168-70. 

75 Film Daily, July 18, 1927, p. 24. 

76 C. Graf, U. S. Pat. 1610514. 

77 L. Bertele, German Pat. 441594, Zeiss Ikon Akt. Ges. 

78 Motion Pictures Today, August 13, 1927, p. 3; Film Daily, August 14, 
1927, p. 6. 

79 O. M. Forfet, Ed. Screen, May, 1927, p. 226. 
8» Sci. Amer., Feb. 1927, p. 128. 

81 Filmtechnik, :March 5, 1926, p. 97. 

82 M. Rikh, Kinotechnik, Dec. 25, 1926, p. 624; Filmtechnik, April 26. 1926 
p. 154. 

83 M. E. Bridston, Photo Era, ^larch 1927, p. 58. 

84 Motion Pictm-es Today, July 9, 1927, p. 20. 

85 Sci. Amer., 1927, 83, p. 343. 

86 Mo\dng Picture World, July 16, 1927, p. 150. 

87 Moving Picture World, August 27, 1927, p. 622. 

88 German Pat. 437570, E. Busch Akt. Ges. Optische Industrie. 

89 British Pat. 262334, F. X. Rogers, Akt. Ges. Hahn f iir Optik and Mechanik. 

90 R. J. Trump, Proc. Opt. Convention, Part II, 1926, p. 899; Sci. Ind. Phot., 
March 1927, p. 21. 

91 Motion Picture Xews, April 29, 1927, p. 1555. 

^2 H. Joachim, Trans. S.M.P.E., Xo. 27, 1926, p. 30-41. Sci. Ind. Phot., 
1926, pp. 97-101. Ivinotechnik, Aug. 10, 25, 1926, pp. 381-5, 409-11. 

442 Transactions of S.M.P.E., Vol XI, No. 31, 1927 

93 Film Daily, July 14, 1927, p. 6. 

94 M. Calin, Cinemat. Frang. Dec. 31, 1926, p. 19. 

95 Motion Pict. News, February 18, 1927, p. 566. 

96 Photographische Industrie, Nov. 8, 1926, p. 1151. 
9^ Motion Pictures Today, July 9, 1927, p. 4. 

98 Motion Picture News, July 8, 1927, p. 36. 

99 Motion Picture News, March 4, 11, 18, 25, 1927, pp. 737, 845, 940, 1033. 

00 Motion Picture News, Sept. 16, 1927, p. 837. 

01 Film Daily, June 19, 1927. 

02 Motion Pictures Today, Aug. 13, 1927, p. 8. 

03 Motion Pictures Today, May 28, 1927, p. 6. 

04 Film Daily, June 26, 1927, p. 5. 

05 Motion Pictures Today, May 28, 1927. 

06 Motion Pictures Today, September 10, 1927, p. 7. 
0' A. Cairn, British Patent 262876. 

08 Motion Picture, 3, No. 1, 1927, p. 1. 

09 J. S. Spargo, Exhibitors' Herald, Sec. I, 29, April 30, 1927, p. 40. 

10 Phot. Korr., March 1926, p. 45. 
'1 L. Gaumont, Bull. Soc. Frang. Phot., April 1927, pp. 110-14. 

12 Motion Picture News, August 12, 1927, p. 449. 

13 Motion Picture News, June 3, 1927, p. 2215. 

14 Film Daily, June 28, 1927, p. 2. 

15 R. Beranck, Filmtechnik, Feb. 5, 1926, p. 44. 

16 A. P. Peck, Sci. Amer., June 1927, pp. 378-9. 

17 Fred Waller, Trans. S.M.P.E., No. 29, 1927, pp. 61-71. 

18 E. J. Wall, Trans. S.M.P.E., No. 30, 1927, pp. 328-33. 
9 C. L. Gregory, American Projectionist, May 1926, p. 4. 

20 E. Wulff, Kinotechnik, Jan. 25, 1926, p. 35. 

21 E. Schuefftan, U. S. Pat. 1613201. 

22 E. Schuefftan, U. S. Pat. 1627295. 

23 L. WitUn, Filmtechnik, Nov. 27, 1927, pp. 174-5. 

24 L.WitUn, Kinotechnik, June 10, 1926, pp. 285-90. 

25 American Cinematographer, August 1926, p. 23. 

26 W. Kohler, German Patent 441202. 

27 M. Hasait, German Patent 439819. 


September, 1927 
Sprocket Dimensions 

AT THE Norfolk meeting of the Society the sprocket dimensions 
in accordance with the general plan of Mr. J. G. Jones had first 
approval as follows : 

The take-up sprocket, which is a hold back sprocket on a motion picture 
projector, should be designed to have the same pitch as the perforations on film 
which has shrunk to the maximum amount occurring with films in commerically 
useful condition as supplied by exchanges. 

The feed and intermittent sprockets are to have a pitch equal to that of the 
sprocket holes in newly finished film. 

The Committee finds that the maximum shrinkage of useful film is 1.5% 
and recommends a take-up sprocket designed accordingly. The shrinkage of newly 
processed film, for which the feed and intermittent are designed, is 0.13%. These 
latter sprockets, as has already been shown, will accommodate film shrunk as much 
as 2,92% without damage. Dimensions of sprockets to produce these results are 
illustrated in Charts A, B, and C. (pp. 407. 408 in No. 29 Transactions.) 

The essential dimensions are: 

For take-up sprocket Base diameter . 9321 in. (23 . 67 mm.) 

tooth 0.050 in. ( 1.26mm.) 

For feed and intermittent Base diameter . 9452 in. (24 . 01 mm.) 

tooth 0.050 in. ( 1.26 mm.) 

All other dimensions are shown on Chart B. 


De. Gage: I wish to place the matter of sprocket dimensions 
before the Society for second approval. 

Dr. Mees: In regard to the shape of the perforation, I am not 
making a motion but bringing the matter to the attention of the Com- 
mittee. The shape adopted by the International Congress is that 
either the Kodak square perforation with rounded corners or the 
Pathe perforation should be adopted. This was adopted at Paris 
after a great deal of discussion. Since that time there has been an 
amalgamation of the Pathe and Kodak Companies in France, and I 
think possibly the Pathe perforation may disappear. This must be 
discussed with the French people, but I wonder whether it is wise to 


444 Transactions of S.M.P.E., Vol XI, No. 31, 1927 ' 

go to the committee with this dimension in view of the fact that it 
may be obsolete when it gets there. I suggest that it might be well 
to hold this particular thing up for six months to see what happens. 
If the French users object, of course, there will be no change. 

Peesident Cook: It seems to me, Dr. Mees, in the first place 
that the point raised is out of order because the standard has already 
been adopted. We cannot, without a reopening of the entire matter, 
do anything; it would necessitate a further delay of six months to 
reopen it. If I understand you correctly, it will become obsolete 
automatically and therefore disappear without any particular legis- 
lation about it. 

Dr. Mees : But you are taking this to the American Engineering 
Standards Committee and that is an authoritative body. It seems 
to me that it is a pity for us to put up to the committee something 
which is obsolete. If you have a rule which insists on your taking 
something adopted a year ago, it is unfortunate. 

With regard to the shrinkage between sprockets, I do not know 
what Mr. Jones has done since the last meeting, but I called his at- 
tention to a paper by Joachim pubhshed in the Transactions that 
did not accept Mr. Jones' standard. Joachim said that shrinkage 
dimensions of lj% did not make the best sprocket, and I wondered 
if the Committee had considered this. I suppose Dr. Gage and Mr. 
Jones have gone over this, in which case I move that we adopt the 

Dr. Gage: Mr. Jones' recommendations are in agreement with 
Joachim's discussion. Mr. Jones' original proposals are given in 
No. 30 Transactions. That was the recommendation' which the 
standard must involve — the basic principles. Originally, Mr. Jones 
designed the take-up sprocket for a maximum shrinkage of 2.92%, 
as given in the previous Transactions (No. 27). Your Committee 
found from all the information we could get hold of that the maximum 
shrinkage to design for was !§%, and this is embodied in the recom- 

President Cook: It would seem from the discussion that the 
Joachim report was given careful consideration by Mr. Jones at the 
time, and it was published as one of the few things included in the 
Transactions which are not of our own origin because it was felt it 
was of such importance. The matter has been up several times and 
was finally adopted after much discussion at Norfolk. I realize that 
thes6 matters must not be passed on hastily, but I think the matter 

Report of Standards and Xomendature Committee 445 

has been carefully considered and discussed, and I believe the recom- 
mendation is the best that can be made. 

Dr. Gage: The recommendation of the Paris Congress has been 
given very careful consideration by the members of this committee. 
The subject has been placed before the Society, as is evidenced by 
Charts IV. and V. (Xo. 30 Transactions, pp. 409-10) together with 
their captions. Mr. John Jones took up the matter with Mr. Vinton ■ 
in England, and the charts discussing the Paris dimensions — 
photostats of these same charts — were sent over and the thing dis- 
cussed in detail, so that you can assure them it was given very careful 
consideration by the Society. The reason we adopted what we did 
was that the recommendations of the Congress were not workable 
and would destroy film, and the American standard in actual use and 
as given by Chart B passes film with the minimum injury. 

President Cook: If I understand correctly, our standard will 
run any film without damage, whereas the Paris standard is open 
to the criticism that badly shrunken film might be injured by running 
on a sprocket similar to theirs. 

{Motion carried to adopt above recommendations.) 

Camera and Projector Speeds 

In the discussion of camera cranking speed it was pointed out 
that with speaking movies where the speech is on one edge of the 
film, it is necessary to change the dimensions of the aperture and to 
have the standard of projection speed and taking speed exactly 
the same. For this reason your chairman sent a circular letter to 
several manufacturers of talking movies asking for details regarding 
the taking and projection speed which they had adopted. The replies 
are summarized in the following table : 

Name of Firm Taking Speed Projection Speed ^ 

Bell Telephone Laboratories 90 ft. per min. 90 ft. per min. 

Radio Corp. of America 85 ft. per min. 85 ft. per min. 

Fox-Case Corp. (Movietone) 90 ft. per min. 90 ft. per min. 

DeForest (Phonofilm) 80 ft. per min. 80 ft. per min. 

Westinghouse Electric & Mfg. Co. 85 ft. per min. 85 ft. per min. 

With regard to projecture dimensions, DeForest uses an aperture 
eV hich narrower than the standard. The dimensions of the Fox- 
Case aperture are given in Fig. 3, page 1 No. 31, Transactions. The 
other firms above have not established aperture dimensions. 

446 Transactions of S.M.P.E., Vol. XI, No. 31, 1927 


Dr. Mees: With regard to the report as a whole, it seems to 
me that the Board of Governors and the Standards Committee should 
consider some more flexible method of procedure. I do not agree 
with Mr. Kintner's remarks that it is too early for standards to 
be formed. The earlier standards are laid down, the better. I think 
we should strengthen our Standards Committee and ask them to 
take more action than they have in the past — and they have not 
been lacking in this respect; and that we should possibly revise our 
procedure so that when we have made a mistake it is possible to 
change it. This matter of tying ourselves to errors appears to me 
to be a mistake. We are likely to make errors with new things. For 
instance, if somebody invented a new sprocket hole system at the 
present time it would be adopted by the manufacturers, and two years 
later it would be adopted by this body, which is foolish when things 
change as fast as they do now. We have grave problems in connection 
with standards; one is the talking film business. We have seen the 
mix-up we have got into on speeds for musical films. Incidentally, 
we are in trouble on all speeds. We have said there is to be an 
average speed of 60 feet per minute for cameras and 80 feet per 
minute for projection with normal presentation, which is not true, 
as we know. Of course, all that has arisen from the fact that the 
Maltese cross movement won't give a flickerless screen at 60 feet 
a minute, and the projectors have to be speeded up apart from the 
conflict between exhibitor and producer as to how much film should 
be shown in an hour. Now, when this is done, the taking speed 
should also be 80 feet per minute ; the Society made the mistake of 
not asking the men to take at 80 when they were going to project 
at that speed. Through our Transactions, the Western Electric 
Company have adopted a speed of 90 feet a minute, and the people 
who are starting to work with them find it necessary to project at 
this speed. We can't ask people now in production to adopt some- 
thing different, and our speed of 80 feet a minute is obsolete anyway. 
None of the theaters are running under 90 feet, so that we may as 
well accept facts and acknowledge that the speeds were adopted in 
the days of our ignorance. In the case of sound reproduction, tak- 
ing and projecting speeds must be the same. The General Electric 
adopted 85 feet a minute. 

We come to the question of the gate for the talking movie, 
and that we must standardize. We have a regulation that the height 

Report of Standards and Nomenclature Committee 447 

of the picture is to be three-quarters of the width. In the case of 
talking films, that is impossible, and there are other experimental 
films coming along in which the shape of the aperture will be different. 
The Society should take a hand at this point of the argument. 

Then, the whole field of the amateur apparatus requires standard- 
ization very badly. It has been standardized as much as it has because 
the Eastman Kodak Company started making film for it and has stand- 
ardized the film. The Society approved the 16 mm film size and should 
now adopt standards for gates and sprockets so that they fit the film. 
In the past, manufacturers have discussed the matter with the Kodak 
Company and they suggested what should be done so that the matter 
is not in chaos, but it will be very soon. The German manufacturers 
are starting in this field and others are also considering it. 

I think the Standards Committee have a lot of work before them, 
and we must probably alter our methods. I do not think we can im- 
prove the personnel or willingness of the Committee, but I think 
we must strengthen it. 

President Cook: With regard to standardization on certain 
features, we are delayed because of just such discussions as came 
up this morning. 

Dr. Mees: I am asking that the Standards Committee of the 
Society get ahead on the standardizing of new things as soon as they 
come out, so that other people will adopt them. If the speed of 
projection of musical film had been laid down at a meeting of the 
Society, then the Western Electric Company and others would 
have agreed, especially if they had had a letter from the committee. 

Mr. Richardson: For the most part I regard what Dr. Mees 
has said as in every way excellent. The points he has raised are 
pertinent. For many years I have preached the gospel that camera 
and projector speed should be the same. I have been roundly abused 
and even ridiculed for doing so. When the matter first came before 
this Society I had many arguments with my colleagues on the 
Standards and Nomenclature Committee concerning the advis- 
abilty of making a recommendation that camera or "taking" speed 
and projection speed be the same. I was over-ruled chiefly on the 
ground that inasmuch as to increase taking speed to the relatively 
high projection speed made necessary by the demand for high screen 
illumination would compel the use of much more negative film, hence 
producers would not adopt the recommendation even though it be 
made. The chief function of this Society is to determine what is the 

448 Transactions of S.M.P.E., Vol XI, No. 31, 1927 

correct practice and to establish that finding as a recommended 
practice or standard. If the manufacturer does not wish to follow 
correct practice, it is no concern of this Society. 

Mr. Cuffe: I don't think adopting a particular projection 
speed will help much; camera speeds vary. You can go out on any 
set and find a speed from 10 up to a great speed. When a director 
gets his picture in the cutting room, he cuts for a certain projection 
speed. There are not two directors cutting for the same speed. If the 
picture is projected slower than that speed for which he cuts, it will 
drag. Griffith cuts his pictures to waltz tempo and another director 
will cut to a speed of 100 feet, and when run at a speed less than 
this, the action will drag on the screen; another will cut to 85 feet. 

Mr. Richardson: On what do they base this? 

Mr. Cuffe : On the temperamental inclination of the director. 

President Cook: We all realize that a standard taking and 
projecting speed is not possible because it is under the control of the 
cameraman and director, and the most we can hope for is recommended 
practice. Standards adopted are very easily susceptible to revision 
and amendment, and Mr. Schlink of the American Engineering 
Standards Committee pointed out that it was not desirable to delay 
adoption of a standard because it was to be changed later. Most 
of the time of their committee is taken up with changes which are 
desirable. The procedure for revision is far simpler than for original 
adoption, and on that account the Standards Committee urged the 
adoption of standards even tentatively in an effort to clarify features 
of the industry with the idea that with progress they can be revised 
to suit new conditions. 

Mr. Stewart: No matter what we agree to be standards, there 
are bound to be certain objections. A film is being made of 16 mm. 
width mounted on a thin brass base having a 28 mm. sprocket hole. 

President Cook: That would not detract from our making 
standards as fast as we can. 

Dr. Gage: For the information of the Society I will say that 
Dr. Mees will get a letter from the Committee saying that any recom- 
mendation he has in mind be reduced to drawings for the Trans- 
actions, and these will be presented at the next meeting to find out 
if the Society wishes to incorporate them as standard. The different 
manufacturers who sent us the information they did as to projection 
speeds, aperture dimensions, and so on will get a complete set of all 
^the letters sent in to the Committee, so that they can think things 

Report of Standards and Nomenclature Committee 449 

over and will get the suggestion that they get together and standardize 
something so that we can take it up at the next meeting. 

President Cook: The Chair recommends to the Chairman of the 
Membership Committee that he make an effort to secure at least 
one representative member from each of the new talking movie 
companies — the General Electric and others — so that they may be 
represented not only in the membership but on the Standards Com- 
mittee. The Chair will be pleased to appoint a representative member 
from each of these organizations on the Standards Committee in an 
effort to clarify standards of this new branch of talking movies. 

Dr. Hickman: The President's suggestion that members of 
leading firms be asked to join the Society for the purpose of cooperat- 
ing with the Standards Committee shall be attended to immediately. 
We have circularized such men in the last few months but have 
received the same excuse in each case; namely, that they could not 
spare the money personally. Now it is my very strong feeling that 
such men should be made members of the Society by their parent 
firms, that it is in the interest of the firms to be represented, and that 
they should therefore pay the dues. I suggest that Dr. Gage write 
to the heads of departments of the big technical companies and put 
the matter before them. 

A request for cooperation sent to English firms through Mr. 
Vinton received another rebuff, which you may agree was a just one. 
Mr. Vinton said that so long as our attitude towards the Standards 
proposed by other people at the Paris conference remained unsatisfac- 
tory, he would not feel justified in recommending membership to his co- 
workers. Surely, we should look into the matter and dispel such feelings. 

President Cook: That is what Dr. Gage has done in the present 
instance. I think your suggestion is a good one — that the invitation 
to membership representatives in our Society would very properly 
come from the Chairman of the Standards Committee in his reply 
to those letters, so that we should start at the top, and they would 
delegate the member to come in. I suggest, Dr. Gage, that you recom- 
mend that one of their members join the Society for this purpose. 

Mr. Beggs: I think the Standards Committee should be inter- 
ested in different types of incandescent lamps for studio lighting 
to avoid disagreements on use. It is the same matter as would come 
before the American Railroad Association. 

President Cook: I suggest that you write a letter to the Com- 
mittee and place the matter before them. 


Eric T. Clarke* 

FOR the year which has passed since I last addressed your body 
I have only one fundamental change in policy to report. All the 
rest of what I have to say today represents continued development 
of policies already in effect a year ago. This one change is the elim- 
ination of the split week and the adoption in its place of a double 
feature program. 

For the benefit of those who are not familiar with the first-run 
picture situation in Rochester, I should explain that we run three 
first-run downtown picture houses: the Eastman, seating 3,350; 
the Piccadilly, seating 2,200; and the Regent, seating 1,800. It has 
for several years been our policy to buy blocks totaling some 200 
pictures, securing these pictures on an interchangeable basis, so 
that upon screening they may be assigned to the house best suited to 
play them. I do not feel that it would be appropriate for me at 
this time to discuss the merits or demerits of block booking. The 
problems at present under consideration in connection with block 
booking do not apply to those who, like ourselves, need in the year 
more than 200 features for first-run showing in the same town. 

For a city the size of Rochester it is clear that there will rarely, 
if ever, be more than 100 pictures in a season's output that are 
worthy of a week's run. In the spring, when the companies' projected 
output for the season is published, we cannot be sure just which pic- 
tures are going to be included in this hundred, but our experience 
has shown that where we have the choice of the entire season's 
product, the purchase in block of some 200 pictures will assure us 
of practically all the good ones which we naturally want. 

The problem of what to do with the remainder has always been 
a hard one. Up to the end of 1926 we continued the policy of oc- 
casional split weeks. By ''split weeks" I mean running one picture 
four days (Sunday to Wednesday) and another the three remaining 
days of the week. By introducing a split week once or twice a month 
in one or the other of our two smaller houses (taking care never to 
split both houses in the same week), we were able to keep playing 
close to release date. Good and poor quality pictures seem to come 
along about evenly all the time, and it is necessary to avoid the ac- 

* General Manager, Eastman Theater, Rochester, N, Y. 


An Exhibitor'' s Problems in 1927 — Clarke 451 

cumulation of unplayed releases. Another argument lay in the fact 
that we were able to carry a pair of second-class pictures in a split 
week on the momentum of the house and would suffer the effect of 
loss of business when we were able to come back the next week with 
a stronger picture. Nevertheless, the problem of what to do with 
these clucks bothered me. I hated to give over a week or a half -week 
to a picture when I knew we would die. I always felt uncomfortable 
when setting in a comedy or other subject around a weak feature. 
A good comedy may strengthen the bill if the picture is good, but it 
will never save a weak feature. So there was always a tendency to 
make the second half of a split week a junk bill. For a while we tried 
deliberately shelving these pictures or salvaging part of the cost by 
sale to some lesser house in town, but one can quickly go broke doing 
that, particularly now that the distributors have found that for the 
millions invested in production there has been only a very small 
percentage of profit and in consequence have forced exhibitors all- 
over the country to pay fat increases over last season's averages. 
Finding after careful analysis that only a few of our patrons would 
ever return to the same house during the same week, we decided to 
make bargain bills by putting two features on at the same time and 
running these for the entire week. It is unusual in our part of the 
country to have a double-feature-first-run policy, but I am so well 
convinced of the merit of the plan that we now devote the Piccadilly 
to nothing else. By taking care in the pairing of the features, we 
find a steadier patronage than we ever knew before. Even if the 
average customer does not enjoy one of the features, he will probably 
find satisfaction in the other. By this plan we have at least found a 
healthy outlet for the "westerns" which each company now insists 
on making and including in the general line. We continue a weekly 
film news to space the film apart, but all short subjects, both single 
and double reels, have been eliminated from our Piccadilly Theater. 
Whatever the argument for buying blocks of features in order to 
get the good ones, I can see no justification in our loading ourselves 
up with comedies beyond our actual requirements. For the present 
year, at any rate, the market is overstocked with comedies, and we 
are able to secure all the choice we wish. The average footage on 
the class of features I have been describing I have found from a 
checkup of over 40 pictures to be around 6,025, so we have adopted a 
two-hour and twenty-four minute schedule of five 13,000-foot com- 
plete shows in the daily operation. 

452 Transactions of S.M.P.E., Vol XI, No. 31, 1927 

In the Eastman Theater and Regent Theater I still stick to the 
two-hour show, and this brings me to the second question I wish to 
discuss and that is, namely, the relative importance of film and pres- 
entation. It is a live issue. The continuance of the policy of the 
two-hour show is only another way of saying that I side completely 
with those who look on the film as of first importance, and that I 
side against those who attempt to build an elaborate show that will 
overshadow the film. 

The present craze for big spectacles, lavish presentations, costly 
stage bands is, as I see it, only a passing fad. Its origin however is 
interesting and is due to three conditions : 

1. Vaudeville has had to come to pictures. 

2. Large expensive houses tied to one line of product have felt 
the need of something to help carry those self -same weak sisters of 
which I have just spoken. 

3. Imitation of Roxy and attempts to beat him at his own game. 
Let us analyze these conditions: 

After many years' success in their own field, the straight vaudeville 
theaters found themselves faced on the one hand with increased cost 
caused largely by higher transportation expense. On the other hand, 
their receipts were dwindling. The increase in movie attendance 
certainly took business away from the vaudeville houses. Inclusion 
of pictures in vaudeville programs resulted in consequence, enab- 
ling a satisfactory show to be given at a lower price than a full show 
of straight vaudeville would require. The policy has succeeded with 
the result that today there is hardly a house in the country running 
straight vaudeville. 

Bearing in mind, however, that one of the big reasons in vaude- 
ville is to fill out the show at a lower cost per minute, it follows 
closely that houses buying good vaudeville cannot afford good pic- 
tures and must necessarily regard the film as subordinate to the 
vaudeville. Such being the case, it naturally follows that the com- 
bination show must still be a variety show in which Httle or no 
relation exists between the vaudeville items and the feature picture. 
There can be no cohesion to the bill as a whole. 

Meantime the big motion picture theaters have been growing 
bigger. Having succeeded in attracting evergrowing audiences and 
in appealing to what would otherwise have been the old-time vaude- 
ville patronage, the tendency has been away from the straight 
motion picture show and towards the show with "presentations," 

An Exhibitor's Problems in 1927 — Clarke 453 

big orchestras, and the hke. Here the one aim has of course been to 
get the largest possible attendance for the big pictures, but the more 
important aim has been at the same time to bolster up weak features 
and so fill up the deepest valleys in a fluctuating series of weeks. 
Picture houses like the Eastman Theater, which selects the best 
from a purchase four times its requirements, are the exception 
rather than the rule. Most big houses, particularly those in New 
York, (which naturally are largely imitated) are tied to a particular 
brand of product and must play the weak ones as well as the successes. 
The management of such theaters being unable to do anything to 
improve the features themselves turn their attention to the rest of 
the program and stick in anything that will help attract business. 

All deluxe theaters in New York live on the remains of Rotha- 
fel's policies. His has been the one original mind in deluxe presenta- 
tion. When he, graduating from a 5,000" seat theater, opens one 
seating 6,200, his competitors are tempted to follow his ways. The 
Capitol, having a better line of pictures than the Roxy can get, 
contents itself with increasing the orchestra to 85 men. The Para- 
mount slaps on massive acts of tinsel and gaudiness. The Roxy 
itself is not immune from the disease. There they slash away at the 
11,960 feet of "What Price Glory'' until it can be run in 90 minutes. 
Why? Well, anyhow they made room for a prologue lasting for 
half an hour. But the prize spectacle could be seen at the Paramount 
this past summer when the Whiteman Band so completely dominated 
the electric signs and newspaper ads that the feature was quite 
lost in the shuffle — and this in the house owned by the producers! 
The situation has grown top-heavy. Rothafel with his immense 
reputation can doubtless get away with it, for the public knows 
that he gives a show, and the public will come whatever the weakness 
of his feature picture. Already others hke Hugo Riesenfeld are 
talking about the "dignity of the simplicity of presentation" and 
making capital of the opposite. 

In all this floundering what is the ideal for which to work? New 
York with its unique floating population need not worry about 
ideals. Yet, that is the problem facing all exhibitors who, like our- 
selves, must appeal to virtually the same audiences week after week. 
First and foremost let us recognize that the movie-goers aggregate 
the largest audiences that have ever patronized any of the arts. 
So large is the following that there is no effective substitute for the 
movies. When Chicago houses were recently shut down, the "legits" 

454 Transactions of S.M.P.E., Vol XI, No. 31, 1927 

did not gain appreciably. It follows that whoever places the film 
first in importance will appeal to the greatest numbers and do the 
biggest business. To such an exhibitor there is nothing to be gained 
by setting up a variety show along vaudeville lines. That policy 
may be best for combination houses buying only the cheapest pic- 
tures, but the public interested in this form of entertainment has 
never been more than a small fraction of the vast array of movie 
goers. The exhibitor who has the best pictures will do better to 
play them with no presentation at all than to surround them with 

First in importance comes the feature, for it, after all, will 
chiefly determine the success of the show. 

Second in importance comes the weekly film news. The addition 
of two news reel services this season, I regard as the most significant 
accomplishment of the year. We purchase all six national news 
reels. True, the addition of these services has increased our expense, 
but the extra cost is well worth while. For good measure we add a 
seventh, which is the Rochester Film News. This Rochester Film 
News consists of motion pictures taken by the staff photographer of 
one of our local newspapers. Those events suggested by our Publicity 
Director as being of general interest to the citizens of Rochester are 
photographed and the shots developed by the Eastman Kodak 
Company. The pictures are then sent to the Eastman Theater for 
use if we consider them satisfactory for showing. The expense of 
this service is borne by the newspaper and the Eastman Theater, 
the newspaper furnishing the photographer and the camera, and the 
theater paying for the development of the film. I cordially recom- 
mend this to exhibitors in other cities as bringing the biggest return 
on the money invested. 

Third in importance come the short subjects. As I stated a 
year ago, we cannot often make use of two-reel comedies, nor are 
there often so many really good ones, but the single and half-reel 
subjects are of great importance. Among these the new Metro 
Oddities added to the Fox Varieties, the cartoons, and novelties of 
other companies are proving most welcome. 

Having now our film, what comes next in importance? Here I 
unreservedly place projection. Careful and adequate projection 
must be assured before it is worth bothering with orchestral ac- 
companiment or stage effects. And by projection I mean to include 
all the lighting embelhshments, patterns, etc., besides a cleanly 

An Exhibitor^ s Problems in 1927 — Clarke 455 

projected picture. In my opinion there is almost a virgin field in the 
art of projection embellishment. At the Eastman Theater we have 
made, I am proud to claim, considerable progress in this art, and 
when our projection engineer, Mr. Townsend, gets some free time 
after completion of the papers which he is presenting at this con- 
vention, we shall undertake a general paper along this line. 

Orchestral accompaniment comes next. There is little to add 
to what I have already stated under this head beyond the fact that 
this season I am experimenting with continuous orchestral accompani- 
ment by splitting the orchestra into two units when the overture 
and acts are over and the feature begins. Half of our orchestra, 
totaling 68 men, is sufficient for the accompaniment of most features, 
and half can rest while the other half plays. 

I come now to the subject of acts, which play an important 
part in the makeup of a bill. The important points to remember are: 

1. The bill as a whole must build up to the feature, never over- 
shadow it. 

2. The bill must contain variety in character and tempo. 

3. Yet the bill must make a cohesive whole so that Mrs. Smith 
will tell Mrs. Jones across the back fence the next morning *'Be sure 
to see the Eastman program this week. The picture isn't so much, 
but I wouldn't have missed the show for the world!" 

I am completely convinced that this type of bill is possible only 
•when the acts are originated in the theater by ourselves. I see no 
way of rounding out the character of a bill by setting an imported 
act against a feature. Since traveling acts are largely vaudevillian 
in origin, the inclusion is merely a step in the direction of the very 
combination show which I wish to avoid. 

As no two features are exactly alike, so no two shows are exactly 
alike. There are therefore no set rules for making up the bill. The 
chief ingredient in making up a bill is idea, just as the chief ingredients 
for a stage act are good ideas for the beginning and ending. After 
four years' grapping with this problem, I have learned one important 
thing, and that is to separate completely the "what from the how." 
With this thought in mind, we have developed at the Eastman 
Theater a unit which for want of a better term I call the "Scenario 
Department." This is a staff function, responsible for nothing more 
and nothing less than preparing act scenarios appropriate to each bill 
as it comes up for consideration. The head of this department, 
who sees all the pictures which are to come to the Eastman, prepares 

456 Transactions of S.M.P.E., Vol XI, No. 31, 1927 

the bill and makes a write-up of each act. I look upon this as an 
entirely new profession. After determining in this way what we are 
going to do, we can discuss the approved write-ups with the stage 
director and consider how they are to be presented. He then brings 
them to regular weekly planning meetings attended by the heads 
of the Orchestra, Scenic, Costume and Projection Departments, 
not less than two weeks before the show is to go on. The stage 
director is the coordinator of all work connected with the preparation 
of the show. He is also responsible for the rehearsals right up to 
the dress rehearsal in the theater on the Frida}^ morning preceding 
the Sunday on which the show opens. The stage director continues 
his work with the cast in the acts for the remaining 20 performances 
of the week after the show is set. 

The number of items on each bill will depend on the length and 
character of the picture. "Ben Hur," and 'The Big Parade," for 
example, call for no overture but require a short prelude leading into 
the stage prologue, which in turn leads directly to the feature without 
interruption. Farce comedies and gala bills, on the other hand, call 
for great variety and will contain as many as eight items. I realize 
that there is no one right way of making the ideal program. There 
are many ways of building a bill around any feature. Our main 
purpose is to select the items which we can put over successfully and 
which in exhibiting suitable variety will lead the audiences gradually 
and without abrupt breaks through various moods up to the opening 
of the picture which must come as the chmax. A short film, light 
in character, is necessary as a "chaser" to follow any feature which 
may end with a sombre note. 


Dr. Mees: I have merely read this paper; I am not responsible 
for the statements made in it. 

Mr. McGuire: I am going to ask Dr. Mees to see that the 
Publicity Committee is provided with at least eight copies of Mr. 
Clarke's paper so that they can be forwarded to the trade papers 
for the earliest possible publication. Mr. Clarke's paper is of great 
practical value and clearly shows what this Society is doing to 
deserve the support of the motion picture industry. 

Mr. Richardson: In my opinion, Mr. McGuire is absolutely 
right; it is a very valuable paper, but I don't believe in the present 

An Exhibitor's Problems in 1927 — Clarke 457 

situation it would be possible for the trade papers to publish the 
paper in its entirety. 

Dr. Mees: As to whether such a paper is desirable for presenta- 
tion at the meeting of the Society of Motion Picture Engineers, I 
believe Mr. Clarke is entirely justified in bringing his ideas before the 
Society. I am very astonished to hear Mr. Richardson say that the 
trade papers have not room for the paper in its entirety. It seems 
to me that the paper would be of the greatest interest to the exhibitors 
who read the trade papers. 

Mr. Richardson: As to publication in the trade papers, I 
have no apology to offer for what I said. The trade papers cannot 
give space which they have not got. Every week we have material 
to fill two hundred papers or more, and we cannot use it all. 

Dr. Mees : Who subscribes to these papers? 

Mr. Richardson: A great many people; we have almost 1000 
projectionists. The bulk are the exhibitors, and we try to bend every 
energy to serve the exhibitor. 

Dr. Mees: I am enthusiastic about the presentation of this 
paper. A theater owner or manager who is running his theater is 
doing an engineering job and is a legitimate member of the Society, 
and the subject of the paper comes properly within the province of 
the Society. 

I was astonished to hear, however, that the trade papers have 
not sufficient room for it. Although Mr. Richardson has explained 
this, it still amazes me when I consider the pages — not in his de- 
partment — devoted to such pictures as those of bathing girls, which I 
pass over hurriedly in order to find his remarks on projection. 


Earl I. Sponable* 

I Introduction 

II Description of Movietone System 
A Recording: 




Aeo Lights 

Slit Units 


Field Outfits 
B Processing: 

Development of negative 


Development of positive 

C Reproducing: 

Projector attachment 

Photo-electric cells 



Loud Speaker 

Theater Acoustics 

III Uses of Movietone 

THE general subject of the making and showing of motion pictures 
in synchronism with sound has been covered recently by papers 
presented before this society at the last two successive meetings and 
also in recent articles appearing in many of the current trade and 
scientific publications. The conception of the idea of sound motion 
pictures is not new, but practical commercialization of the art has 
been dependent upon the perfection of sound transmission apparatus 
and the solution of problems relating to various vital parts of the 
whole system. 

In this paper it is intended to cover briefly the making and 
presenting of the Fox-Case system of sound motion pictures trade 
named "Movietone" and to emphasize various parts of the process 
peculiar to this system that have not previously been described. 

The theatrical success of any system of sound motion pictures is 

- * Technical Director, Fox-Case Corporation, New York City. 


Technical Aspects of the Movietone — Sponahle 459 

destined to bear a definite relation to its practicability and to the 
faithful reproduction of sound without embellishments or special qual- 
ities added to the original. The theater is especially critical of this last 
named condition inasmuch as the audience must hear the reproduced 
sound over a period of time, and any distortion will cause a very tiring 
effect upon the listeners. The novelty of "talking pictures" is past. 
Now, unless the illusion is so very real that the hearers are unaware 
of the process involved, the system will surely be doomed to failure. 

The making of Movietone pictures is carried out in three general 
steps ; namely, recording of the sound and picture, processing of the 
film, and reproducing. 


Whenever sound is recorded in an enclosed area, usually two 
conditions have to be satisfied. These are the exclusion of foreign 
noise necessitating sound proofing of the studio and reduction of room 
resonance or echo. 

The present recording rooms at the Fox-Case Studios were 
designed from experience gained in the construction of three previous 
experimental studios, the study of some of the modern broadcasting 
rooms, and through experiments relating to acoustical materials. 
It was decided that at least two separate recording studios were 
necessary. These rooms were constructed sound proof from street 
noises and from each other. It is possible to have sets being prepared 
on one stage while recordings are being made on the other. 

The sound proofing is accomplished either by using very thick 
masonry walls or by using a double wall with an air space and a 
sound absorbing material within. The inner walls of our studios are 
made with 4-inch solid gypsum block, 1 inch of hair felt, 3 inches of 
air space, and another 4-inch solid gypsum block wall. These walls 
are started about 6 inches down in the concrete foundation. The outer 
walls are made of brick and masonry and are about 24 inches in thick- 
ness. A double ceiling is supported from the roof trusses. It is made of 
concrete plaster and separated by a 3-inch air space and 1-inch hair 
felt. The floors of the studios are covered with soft carpet. The inner 
walls and ceilings are covered with Celotex and further damped by 
hanging heavy Monk cloth drapes perpendicular to the walls and 
ceiling. These drapes are arranged for raising and lowering, so that 
the degree of resonance may be varied to meet different conditions of 

460 Transactions of S.M.P.E., Vol XI, No. SI, 1927 

This special arrangement of damping shown in Fig. 1 was found 
to be equivalent to covering the walls with 3 or 4 inches of hair felt 

Fig. 1. Cloth drapes for controlling resonance in recording room. 

and possessed the advantage over felt that the absorption of the sound 
was quite independent of frequency. 

A small and a large stage have been equipped in the manner 

Technical Aspects of the Movietone — Sponable 461 

described above. The small stage is 22 feet wide by 56 feet long by 21 
feet high and is highly damped. This condition is used mainly when 
recording speech. In the case of musical numbers, a certain amount of 
resonance is preferable. Such conditions have been satisfied in the 
larger stage, which is 50 feet wide by 80 feet long by 21 feet high. 
The size of this stage permits the erection of sets for practically all 
types of present picture requirements. It is also used in recording the 
musical scores in synchronism with regular pictures. In this work 
the picture is projected on a screen from a sound proof booth, and the 
conductor of a selected orchestra follows the pictures, synchronizing 
such special effects as the score requires, often incorporating many 
things that promote the proper presentation'of the picture and which 
would be difficult even in the larger theater orchestras and practically 
impossible for the smaller theaters. The sound from the orchestra is 
recorded on a film running in synchronism with the projection 
machine. The sound negative so obtained can then be developed and 
combined with the regular picture negative to make positive prints 
having the Movietone scoring on the same film adjacent to the picture. 

Those of you who ever visited a broadcasting studio in summer 
will undoubtedly remember the Turkish bath effect which is secured 
in insulating for sound and the resultant retention of heat therein. 
In designing the Fox Case Studios, considerable thought was given to 
the problem of ventilation. The problem was more complicated than 
the usual ventilation problem due to the necessity of excluding blower 
and machinery noises. The air in the present studios is conditioned 
and is completely changed every eight minutes. The temperature and 
humidity of the rooms are controlled and held proper for maximum 
comfort. This installation has proved well worth while in obtaining a 
higher efficiency from both artists and working personnel. This is 
especially noticeable in the picture scoring work, where large orches- 
tras are playing over a period of several hours a day. 

The picture lighting used in the sound studios is similar to that 
employed in regular motion picture work. Both hard and soft lights 
are used. In some cases it was found necessary to quiet down the 
operating mechanisms and also to change the reflectors in the Cooper- 
Hewitt lamps to prevent sound reflections. It is probable that later 
incandescent or improved lighting equipment and panchromatic 
film will help solve noise problems. In any case, there is a field open for 
the manufacturer to make better lighting equipment for use in sound 
picture work. 

462 Transactions of S.M.P.E., Vol XI, No. 31, 1927 

All of this work of adjusting acoustics in studios would not be 
necessary if the sound collectors used in recording could be made to 
act like our ears. Unfortunately, this has not been done and we find 
the microphone collecting sound in a manner quite similar to what one 
hears with one ear alone. This condition, together with the fact that 
in reproduction we usually require little if any more resonance in 
addition to that possesed by the theater itself, makes the technic 
of microphone placing an art in itself and something that has a most 
important bearing on the illusion that will be obtained in the repro- 
duced sound. 

For our work, we prefer to employ in most cases sound collectors 
of the electrostatic or condenser type. This apparatus, together with 
the auxiliary amplifier equipment necessary to increase the electrical 
energy picked up by the microphone corresponding to sound varia- 
tions to a level necessary to operate the recording mechanism at the 
film, is practically Western Electric standard Public Address equip- 
ment. This has already been described to you by Mr. P. M. Rainey 
in his paper on the Vitaphone.^ 

In recording, it is necessary, of course, that the microphone 
be either placed outside of the camera field or masked. The intensity 
of sound varies inversely as the square of the distance, thus the 
problem of suitable position of the microphone is of utmost impor- 
tance, especially when recording weak sounds. In recording large 
orchestras and complex musical organizations, the balance of sound 
must be carefully adjusted through the use of a Monitor system. 
This system of monitoring is a replica of the standard reproducing 
system and thus enables one to judge at all times how the reproduced 
record should sound. In some recording work, we use a number of 
pick-ups, combining and adjusting these currents through the use 
of a mixing panel. 

Two methods of changing the electrical variations, corresponding 
to original sound, into variations in light intensity and subsequent 
exposure of the photographic emulsion are being successfully used in 
Movietone recording. One of these consists in modulating what is 
known as a ''light valve." This is a development made at the Bell 
Laboratories and is similar to the device described by H. E. Ives.^ 

1 "Some Technical Aspects of Vitaphone," by P. M. Rainey, Trans. 
S.M.P.E., No. 30, p. 294, (1927). 

' "Transmission of Pictures over Telephone Lines," Bell System Technical 
Journal, April, 1925. 

Technical Aspects of the Movietone — Sponable 


Its use in connection with sound recording will be described in detail 
in another paper. The other method involves what is termed the 
''flashing lamp" principle and consists in modulating an electrical 
discharge taking place between electrodes in an actinic gas. This gas 
discharge device is a development made at the Case Research Labora- 
tory and is termed "Aeo" light. 

y^o^^mM'' - 


Fig. 2. The Aeo light. 

It is fairly simple to make a glow lamp, but to make a light that 
will follow all the intricacies of the different sounds, from the faintest 
to the loudest, and do this without distortion and, further, give 
sufficient light to properly expose a photographic film, has proved an 
interesting problem. Thus far the "Aeo" light has proved most 
satisfactory for this purpose. This light is shown in Fig. 2. It consists 
of a glass or quartz bulb about 1| inches in diameter and 6 inches 
long. Two electrodes are mounted close to the rounded end of the 
bulb. One of these electrodes, the anode, is usually made of sheet 
nickel about | inch wide and J inch long. This is mounted opposite 
a U-shaped cathode of platinum coated with a mixture of alkaline 
earth oxides. During the manufacture of the "light" the oxide coated 
loop is activated, and a gas consisting mainly of helium is placed in 

464 Transactions of S.M.P.E., Vol XI, No. 31, 1927 

the bulb at a pressure required to produce a concentrated glow 
about the cathode under an applied potenial of about 350 volts and 
a current of about 10 milliamperes. 

In use for sound recording, the "Aeo" light is maintained lumin- 
ous by an exciting battery. Sound currents are superimposed on 
this luminous discharge causing it to modulate and vary in intensity 
in accordance with the original variations. 

To print the sound image on the negative film, the "Aeo" light 
is inserted in a tube carrying a quartz slit mounted on a mechanical 
float, which presses very lightly against the film at the feed sprocket 
in the camera. The development of this slit was a very important 
step leading to the making of commercial sound records. The early 
inventors attempted to use a slit made up of metal knife edges. This 
was impractical due to the fact it could not be made sufficiently 
accurate for good sound recording and when placed against the 
film could not be kept free of dirt. The present sHt consists of a small 
piece of quartz about 0.2 inches square and 20 mil thick. One surface 
of this piece is coated with a silver film and a slit is ruled in this 
film having dimensions of 0.10 inch X 0.0006 inch. A cover glass is 
then cemented upon the silver and this cover glass polished down so 
that the thickness of the cover over the slit, including the cement, is 
less than one one-thousandth of an inch thick. The "Aeo" light is 
mounted directly back of the slit and as close as physically possible. 
This type of slit has been successfully used for both recording and 
reproducing. It is now being superseded by an optical slit wherein the 
image of the slit ruled on the silvered quartz is focused upon the 
photographic film. The sound is recorded on standard negative film 
adjacent to the picture. Fig. 3 shows the dimensions and location of 
this record. The speed of the film during recording is 90 feet per 

During the development of this sj^stem it was considered desir- 
able to adhere to standard equipment whenever possible, and this is 
especially true in the choice of camera equipment. The present Movie- 
tone camera was developed from the Bell & Howell motion picture 
camera. The advantages of this camera for picture making have in a 
large part been retained. Arrangements have been made for the 
insertion of the sound recording attachment to print the sound on the 
feed sprocket. In order to obtain uniform velocity of film at this 
point and quietness of operation, it has been necessary to install 
precision gears and make all internal parts with the most exacting 

Technical Aspects of the Movietone — Sponahle 




J 10 




Negative Fri-M 

T m.i.. 

DATE cJct: 5/2 7 

Bv £: /s- 

Fig. 3. Dimensions and location of sound record. 

mechanical accuracy. A fly wheel has been placed on the sprocket 
shaft and mechanical filters incorporated to produce uniform motion 
of the sprocket. In the studio, the cameras are driven by synchronous 
motors. For portable work, 30 volt direct current motors are used 

466 Transactions of S.M.P.E., Vol. XI, No. 31, 1927 

with rheostat control operated from storage batteries or special 
spring motors controlled by a governor similar to those of phono- 
graph motors. Fig. 4 shows a general view of a motor-driven studio 
camera. Fig. 5 shows the method of threading the film and the sound 
recording tube in position. 

A complete field recording outfit consists essentially of a micro- 
phone, a special amplifier containing a volume indicator, the "Aeo" 
hght circuit, and a special sound camera. Power for the amplifier is 
supplied by a 12-volt storage battery and a 400-volt dry cell B 
Battery. The outfit is transported in a | ton automobile truck and 
manned by a crew consisting of a camera man and a sound man. 
The apparatus has been amplified to such an extent that the recording 
work in most cases is being done by men having no special technical 
training. It is important, of course, that all recording equipment be 
inspected at regular intervals. To this end a department has been 
established to service and make measurements on the apparatus 

A number of these outfits are in operation at the present time 
both in this country and abroad. It is intended within a short time 
to cover the world for Movietone recording in the manner that the 
silent news motion picture is covered now. The wide open spaces give 
acoustically ideal recording conditions. It is probable that in making 
Movietone feature pictures that the outside recording will be done by 
a portable outfit and that the lot will be located in some quiet section 
away from the noise and din of the city. 

The processing of the film is being carried out in our regular 
commercial laboratory. The negative is developed by rack and tank 
method for normal time in a fine grain developer. The printing of the 
positive is at present accomplished by standard Bell & Howell semi- 
automatic continuous printers of the back shutter type. These are 
modified by installing masks at the printing aperture to allow for 
covering the sound track while the picture is being printed and vice 
versa. The negative and positives are then run through the printer 
twice. In printing, the sound is shifted with reference to the picture 
to provide proper synchronism - on projection. In the camera, the 
distance from center of picture with the intermittent about to move, to 
the sound slit is 7f inches, the sound slit being on the take-up side. 
In ihe projector this distance is increased to 14 J inches. 

Technical Aspects of the Movietone — Sponahle 467 

Fig. 4. Motor driven studio camera. 

Fig. 5. Camera showing sound recording tube. 

468 Transactions of SM.P.E., Vol. XI, No. 31, 1927 

It is only recently and with the cooperation of the Eastman 
Kodak Research Laboratory that we have begun to actually inves- 
tigate the effect of photographic processing upon the quality of re- 
produced sound. Some very interesting results have already been 
obtained. One of the things that bothered in the beginning of the 
sound recording work was film noise or ground noise. This was at 
first thought to be inherent in the base or emulsion of the film itself, 
but it has recently been shown at the Eastman Laboratory that per- 
fectly clean film will reproduce practically without noise. If, however, 
the film is handled and rewound in the open, dust particles adhere to 
the film and ground noise appears. This means if the film in recording 
and processing is kept clean, that practically the only film noise that 
will be present on the print will be due to the dust and abrasion on the 
positive. By proper setting of the recording level, this noise will be so 
low in comparison with the reproduced sound that its presence will 
be practically unnoticeable in the theater. 

In the developing of the positive and negative films, it has been 
found that contrast and consequently the quality of the reproduced 
sound follow the conditions necessary for good picture reproduction; 
namely, that the product of the negative and positive gammas be 
nearly unity. Fortunately for commercial purposes, these limits are 
not particularly narrow. It is more important for good quality of 
reproduction that the transmission of the sound record be correct. All 
laboratory work is gradually being placed on a mechanically and 
scientifically controlled basis. This will not only promote the produc- 
tion of better sound records but will improve the picture value as well. 

Recording the picture and sound upon the same film make it 
possible to cut and edit the film in a manner very similar to that used 
for cutting pictures without sound records. Either the positive or 
negative can be handled in this manner. In one of the pictures shown 
here, over one hundred separate shots are included, each of which were 
retaken several times in the making. 

The process of reproducing the sound from the Movietone film 
consists essentially in moving the sound record through a linear beam 
of light. The modulations in the form of sound lines on the film vary 
the light beam in accordance with the recorded sound. These light 
variations falling upon a photo-electric cell produce corresponding 
electrical variations which may be amplified and changed back into 

Technical Aspects of the Movietone — Sponahle 


sound variations at the loud speaker to give the reproduction of the 
original sound. 

Fig. 6 shows a theater style of Movietone attachment for repro- 
ducing the sound. This type has been designed to be applied to the 
standard Simplex projector and is placed between the head and the 
lower magazine. It consists of an accurately cut sprocket used to move 

Fig. 6. Projector with sound reproducing attachment. 

the film at a uniform velocity between an aperature plate and tension 
shoe. A 25-watt, 12-volt straight coil filament lamp is focused upon a 
slit 1 .5 mils wide. The image of this slit is then focused upon the sound 
track on the film at the aperture plate, giving a rectangle of light 
0.080 inch X 0.001 inch. The modulated fight passing through the 
film falls upon a potassium photo-electric cell. This cell is connected 
to a three tube resistance coupled amplifier which is in turn coupled to 
a Standard Public Address amplifier system and loud speakers. 
Uniform motion of the sound sprocket is obtained by placing a rather 
heavy fly wheel on the shaft supporting the sprocket and driving the 
shaft through a damped spring mechanical filter system by a tuned 
motor generator drive. 

470 Transactions of S.M.P.E., Vol XI, No. 31, 1927 

For the smaller theaters a simplified attachment is used. The 
tuned motor generator drive is replaced by a synchronous motor or a 
direct current motor with rheostat control. The motor is belted to 
the fly wheel of the attachment by an endless cord belt which serves 
as a mechanical filter of motor pulses and does away with the spring 
filter mentioned above. The inertia of the fly wheel smooths out any 
gear inequalities that tend to reflect back from the head mechanism of 
the projector. In this simpler attachment a barium photo-electric 
cell picks up the sound variations and is coupled to the main am- 
plifier through a one stage amplifier. 

A number of sizes and arrangements of equipment are available 
to take care of all conditions of projection from the largest theater 
down to the smallest demonstration room. These are made to operate 
either on direct current or alternating current as the conditions 

The Public Address equipment and loud speakers used in repro- 
ducing have been fully described by Mr. Rainey in his paper on the 
Vitaphone. Theaters already equipped for Yitaphone can run 
Movietone by the addition of the attachment to the projector and a 
slight re-adjustment of the amplifier system. 

In reproducing sound film it is of course necessary that the speed 
of the film be the same as that used in recording. The standard 
adopted for all Movietone film is 90 feet per minute. The fact that 
the sound and picture are on the same film means that synchronism 
and correct correlation of picture and sound are automatically taken 
care of. If the film is broken or parts are cut out, the sound and picture 
are equally affected. 

For Movietone reproduction we have developed a special pro- 
jection screen that is practically transparent to sound and yet 
possesses a satisfactory surface for the picture projection. This screen 
is made of bleached cotton yarn woven in a novel manner to allow the 
passage of sound without muffling and yet reflect a maximum amount 
of light. With such a material the loud speaker can be placed directly 
behind the screen consequently producing the illusion that the sound 
is actually issuing from the point indicated by the action on the screen. 

The loud speaker equipment consists of a sufficient number of 
horns so located that even distribution is obtained in a theater. 
The horn type loud speaker has a distinct advantage over the cone 
type in that it is somewhat directional, and with it the acoustical 
aberration in a theater may be corrected. A horn distributing panel 

Technical Aspects of the Movietone — Sponable 471 

is used to permit a variable number of horns to be utilized and the 
volume from each individual horn to be controlled. Theatrical 
acoustics are of such complex nature that each individual layout must 
be considered in making an installation. For the smaller theater 
where there is not room for a horn installation, a disc type of speaker 
has been developed. 

It has been found that the regular projectionists in the theater 
are capable of maintaining and operating the public address systems. 
A periodical inspection service and a regular routine of Movietone 
operation is prescribed which insures against loss of program due to 
non-functioning or the failure to properly operate the equipment. 
Development is being made along the lines of reducing all possible 
error in the handling of the equipment by the installation of such 
improvements as the optical slit, battery eliminators, centralized 
control, automatic volume regulation, etc. ^ 


The production and uses of the Movietone are now being 
developed along a number of different and varied lines. These include 
pictures of the same type as the silent picture but with sound. 
These pictures will use the real sounds of life with possibly music 
inserted where the action calls for it. 

Musical numbers where the music is especially composed, as well 
as the story, form a new kind of picture created by Movietone. 
Short numbers recording the stars of the stage are made for showing in 
the smaller cities and towns where the stars themselves never appear 
in person. 

Educational, historical, and religious pictures are being devel- 
oped. These will speed up and improve our present methods of 
teaching, incidentally bringing the personalities and teachings of the 
great within reach of the masses instead of the present few. 

Musical scores for the silent pictures can be applied after the 
silent picture has been finished. These are directed and played by 
the finest musicians obtainable. Special effects are incorporated that 
greatly enhance the presentation of the pictures especially in the 
smaller theaters. 

The news reel is being made more interesting and valuable 
through the addition of sound. In the case of one recent event, the 
Movietone recording taken and used totaled 1566 feet. On the same 

472 Transactions of S.M.P.E., Vol XI, No. 31, 1927 

shot the usable silent picture footage was slightly over 100 feet. 
The sound picture in this instance is still being exhibited. 

Other uses of this system are evident and will follow. The home 
use will develop into an important field. Sound pictures of our 
children, families, mothers, and fathers especially are desirable. 

The preliminary development of the Movietone system was done 
at the Case Research Laboratory. It was there, during a period when 
"talking pictures" were considered more or less of a folly, that Mr. 
Theodore W. Case financed and through inventive genius was in- 
strumental in making the system practical. Later in the face of many 
complexities, Mr. William Fox undertook its commercialization, and 
now, through the affiliation and cooperation of the Western Electric 
Company, this system of sound motion pictures seems destined to a 
field of public usefulness. 


Mr. Richardson: What effect will oil on the film have on the 
sound reproduction? Will it not be necessary to handle Movietone 
films carefully, particularly in the process of rewinding in order that 
the sound record is not injured; and what will be the effect of longi- 
tudinal and vertical scratches on the sound reproduction? How many 
frames is it possible to cut out in the event of making a splice without 
affecting the continuity of the sound reproduction? This Society has 
adopted a minimum of 75 and a maximum of 85 feet per second as the 
projection speed. Why is it not practical to keep within those limits in 
making Movietone films? You have developed an effective screen 
through which the sound will freely pass. Many theaters have an 
expensive screen through which it would be difficult to make sound 
pass, and many screens are close to the wall. What procedure do you 
recommend in such cases? 

Mr. Sponable : With reference to oil, we find that it makes prac- 
tically no difference in the reproduction of the sound. We have had 
some film almost dripping with oil, and still this gave fairly good 
reproduction. Scratches caused in the ordinary handling of the film 
do not have any appreciable effect on the sound reproduction. A 
fairly deep scratch caused, for instance, by emulsion caking on an 
aperture plate, which forms a line one or two millimeters wide, will 
give surface noise, but the ordinary fine scratches produced in the 
rewinding of film do not greatly increase surface noise. This summer 
at the Harris Theater in New York we ran Movietone numbers, about 

Technical Aspects of the Movietone — Sponahle 473 

four thousand feet in all, using the same prints continuously over a 
period of four months. 

With regard to cutting out frames, it depends on the subject. 
In speech, the film travels at 90 feet per minute, and it takes about 
half a second to speak a word. One word may be distributed over a 
length of about 9 inches, so that loss of a few frames will merely take 
out a part of a syllable but will not destroy its understandability. 
In music, loss of film is not especially noticeable, particularly where 
the beat or rhythm is not changed. 

Originally we recorded at a film speed of 85 feet per minute. 
After our affiliation with the Western Electric Company, this was 
changed to 90 feet per minute in order to use the controlled motors 
already worked out and used in the Vitaphone system. There are a 
large number of both Vitaphone and Movietone installations sched- 
uled and in operation, and sufficient apparatus is involved to make it 
impractical to change the present practice of sound reproducing. In 
connection with the Society's standard, I have been unable to find 
any New York theater which is running film at 85 feet a minute; 
the present normal speed is 105 feet, and on Sundays often 120 feet 
per minute is used in order to get in an extra show. 

The prime requisite in sound picture reproduction is to obtain 
a good illusion. Loud speakers might be placed at the side of the 
screen or even in the orchestra pit for musical accompaniments to 
a picture, but for any talking picture where the sound appears to 
originate from the action on the screen, the loud speakers must be 
placed directly back of the screen and preferably in the upper center 
position. In case the screen is close to the back wall of the theater, 
we can use a disc type of loud speaker back of the screen. 

Mr. Bauer: Is the sound recorded at the aperture or at the 
sprocket where the lamp is, and if so, if the film were to break at the 
picture aperture, what effect would it have on the sound record so far 
removed from the aperture? 

Mr. Sponable: The sound is recorded in the camera at the 
feed sprocket 7| inches beyond the picture aperture on the take-up 
side. During printing it is shifted with reference to the picture, 
and in the projection the distance from the center of the picture 
to the corresponding sound record is 14^ inches. If the film is broken 
and spliced, the same space relation between picture and sound is 
always maintained and there is no loss of synchronism. 

Mr. Coffman: How are the proportions of the picture main- 

474 Transactions of S.M.P.E., Vol. XI, No. 31, 1927 

tained when the synchronized musical score is printed beside pictures 
photographed with a standard camera aperture? 

Mr. Sponable: In scoring a picture, we run the film through a 
special printer removing a little from each edge of the picture by 
displacing the picture negative with reference to the print and thus 
reserving space for the sound record. 

Dr. Troland : In connection with the application of color to this 
process; we have had some experience with the Phonofilm, and there 
was some difficulty in that in the first experiments the sound repro- 
duction had to be done in red or green and the resolution of the sound 
recording was not as good as desired, but with the single coated 
process, it is possible to record in black and white and put the colors on 

Mr. Sponable: I remember the experiments in connection with 
Phonofilm. At that time the thalofide cell was used in reproducing the 
sound. This was only sensitive to the red portion of the spectrum 
With the photo-electric cells now being used, we should obtain very 
much better results. 


Arthur C. Hardy* 

THE desire to make a simultaneous record of sounds and actions 
is not new. As long ago as February 1888, Muybridge conferred 
with Edison as to the practicability of using the zoopraxiscope "in 
association with the phonograph so as to combine and reproduce 
simultaneously, in the presence of an audience, visible action and 
audible words." The phonograph was then less than eleven years old 
and had not been adapted to reach the ears of a'large audience, so the 
scheme was temporarily abandoned. Although space does not permit 
a review of the progress of the art since the early days, it is generally 
agreed now that the ultimate method of sound recording consists in 
utilizing a narrow strip of the film itself for the sound record. This 
scheme avoids nearly all opportunity for lack of synchronism between 
the sound and action and at the same time provides a simple method 
for the removal of an entire scene when desired. 

The purpose of the present paper is to analyze the distortion 
arising in the photographic part of the process. It is not difficult to 
prove that such distortion does often exist. The quality obtained in 
the best of sound records made on photographic film is noticeably 
inferior to that of radio broadcasting. With a good local broadcasting 
station and a high quality radio receiving set,^ the reproduction is as 
good as would be desired by most persons, excepting possibly highly 
trained musicians. The electrical and acoustical apparatus used in 
broadcasting is essentially the same as that used in the production 
of sound records on motion picture films. We are forced to conclude, 
therefore, that some, if not all, of the distortion so often present in 
talking films is due to lack of consideration of the photographic re- 

The requirements of correct rendering of tone values in sound 
recording are not essentially different from the requirements of correct 
tone rendering in ordinary pictures. ^ Since a considerable amount of 

* Assistant Professor of Optics and Photography, Massachusetts Institute of 
Technology, Cambridge, Mass. 

^ This combination is unfortunately rare. 

2 The expression tone values is here used in the photographic rather than in 
the musical sense. 


476 Transactions of S.M.P.E., Vol. XI, No. 31, 1927 

work has been done on the latter problem already, the terminology 
and the methods now in use in that connection will be adopted as far 
as possible. An excellent summary of the previous work and a useful 
graphical method for the solution of these problems has been pre- 
sented in two papers by L. A. Jones in the Journal of the Franklin 
Institute for 1920, The present author has assumed a general 
knowledge of the contents of these papers. 

The Method of Recording the Sound 

The many methods of making sound records on motion picture 
film are too well known to require much elaboration in detail. How- 
ever, it will be necessary to assume some sort of equipment, and so a 
brief description of one method of recording may not be out of place 
here. Since the treatment in this paper is largely theoretical, the re- 
sults are not limited to records made with any particular arrangement 
of apparatus, as the film has no way of knowing what sort of electrical 
or acoustical devices precede or follow it. 

We shall assume that a microphone is used in the studio to pick 
up the program — either the voices of the actors or the selections 
played by the orchestra providing the incidental music. The voltage 
generated in this microphone is impressed on the grid of the first 
tube of an amplifier of ordinary type such as is used in radio recep- 
tion. We shall assume a perfect microphone and amplifier, since we 
are not concerned with distortion except when it occurs in the photo- 
graphic phase of the problem. Then the variations in the plate 
current of the amplifier will be a faithful copy of the variations in the 
sound pressure at the microphone. This current may be used in either 
of two ways, leading to two very distinct types of sound records. 
These are known as the variable density and variable width types re- 

We shall consider first the variable density type of record, such as 
is illustrated at the left in Fig. 1. In this type of record, the density 
is uniform across the sound track but is made to vary along the length 
of the track by altering the exposure in accordance with the variations 
in the plate current of the amplifier. A glow lamp or a string galvano- 
meter operating as a light valve are familiar examples of suitable 
apparatus for this purpose. 

In the variable width type of record, the exposing light is of 
constant intensity, but the illuminated part of the width of the track 
is caused to vary in accordance with the plate current in the amplifier. 

Rendering of Tone Values — Hardy 


An oscillograph mirror adjusted to illuminate half of the sound track 
when there are no sounds at the microphone will produce this type of 
record (see right hand side of Fig. 1). 

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film, known as the Variable Density and Varmhle Width types respectively. 

The Method of Reproducing the Sound 
After a film has been properly exposed in a recording device of 
either type, it is developed in the usual way into a sound negative. 
This negative may be printed on a continuous printing machine and 
the result is a positive suitable for reproduction. Either type of 
record may be reproduced in the same apparatus. A typical arrange- 
ment of apparatus consists of a mechanism for driving the film at 
constant speed, an aperture close to the film,^ and some source to 
provide an abundance of light at this aperture. Behind the aperture 
is a light-sensitive cell, the current through which depends on the 
total amount of light that it receives. In a well constructed photo- 

^ It is somewhat better to image this aperture on the film by means of a 
suitable optical system, but the close-up aperture is simpler to discuss. 


Transactions of S.M.P.E., Vol. XI, No. 31, 1927 

electric cell, the current is exactly proportional to the total light flux, 
and although this current is ordinarily not more than a few micro- 
amperes, it may be amphfied by suitable apparatus and caused to 
operate a loudspeaker. Here again, we need not concern ourselves with 
the distortion which might exist in the amplifier if it were not properly 
constructed, and which usually does exist in loud speakers. Let us 
remember that the distortion produced by the electrical and acoustical 
elements is not considered serious when these elements are used alone. 

Theoretical Requirements for Correct Tone Reproduction 
Before proceeding to the consideration of the requirements for 
correct tone reproduction, it will be useful to make a few sim- 



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pure sine wave. 

Fig. 2. Graphical representation of a pure sine wave. This type of sound 
wave has been assumed in this paper for the sake of simplicity. If the re- 
production of tone values is correct, the variations in sound pressure pro- 
duced by the loud speaker are representable by a curve of the same shape. 

plifying assumptions concerning the nature of the sound to be 
recorded. The physical phenomenon which we term "sound" consists 
in rapid variations in atmospheric pressure. These pressure variations 
are ordinarily produced by the vibration of mechanical parts or by 
the vibration of columns of air, as in wind instruments. If the rate of 
vibration lies between 20 cycles per second and 10,000 cycles per sec- 
ond, the result is a note of audible frequency.^ From a mathematical 

* The exact limit of audibility is dependent upon the intensity of the source 
For all practical purposes, it is sufficient to reproduce all frequencies between 20 
and 10,000 cycles per second. 

Rendering of Tone Values — Hardy ^ - 479 

standpoint, the simplest type of variation in sound pressure is a simple 
sine wave as in Fig. 2. This may be represented by Equation 1 : 

p^Po+Psinco^ (1) 

where Po represents the average atmospheric pressure upon which is 
superimposed a sinusoidal variation of amplitude P. Although a 
simple sine wave of this sort is rarely produced by any musical in- 
strument, we may always analyze any musical note into a fundamen- 
tal sine variation plus a number of harmonics or overtones.^ The 
quality, or timbre, of a musical instrument depends on the relative 
amplitudes of these harmonics. However, for the purposes of the 
present paper we need to consider only a simple sine variation, such 
as is shown in Fig. 1, since any method which will reproduce the 
fundamental faithfully will likewise reproduce the harmonics, subject 
only to limitations to be discussed later. Let us assume, therefore, 
that our problem is to record a simple sine wave of relatively low 

If a perfect microphone and amplifier are used in recording, the 
current in the last stage of the amplifier may be represented as in 
Equation 2. 

i= Iq-\-I sin CO t (2) 

This current consists of a constant term Iq plus a variable term of 
maximum amplitude / multiplied by sin cot. The condition for correct 
tone reproduction in the photographic phase of the problem is simply 
that the current in the photo-electric cell of the reproducer be expressible 
by an equation of the form of Equation 3. 

i'=Io'+KI sinco t (3) 

The constant term lo' in equation 3 need not be related in any 
manner to the constant term Iq in Equation 2. However, the ampli- 
tude of the variable term of Equation 3 must be proportional to the 
amplitude of the variable term in Equation 2 as indicated by the 
presence of the proportionality constant K. 

There is a useful concept in sound recording which has no 
counterpart in the ordinary use of photographic materials for picture 

^ Consider the case of a musical instrument playing the A below middle C. 
The fundamental frequency of this note is a Kttle more than 200 cycles per second. 
For simphcity let us assume it to be exactly 200 cycles per second. In general, 
this note will consist of the fundamental 200-cycle variation, plus an harmonic 
with a frequency of 400 cycles per second, plus a third harmonic with a frequency 
three times the fundamental or 600 cycles per second, and so on, the amplitude 
falling off rather rapidly in the higher harmonics. 

480 Transactions of S.M.P.E., Vol. XI, No. 31, 1927 

making. Referring again to Equation 1, we find the maximum value 
of p to be Pmax = Po-\-P, the minimum value, pmin = Po—P, and the 
average value, pave = Po- We then define the modulation by Equation 

Pmax- JPave- 'Pave- Vmin- ^ 

m = = -- = — - (4) 

Pave' Pave' -^ Q 

For obvious reasons the value of m can never exceed unity, since 
any greater modulation would require a pressure less than zero for 
some parts of the cycle. The amount of modulation of the air pressure 
by ordinary sounds is small, but the modulation of the plate current 
in the last stage of the recording amplifier may be made very large. 
It cannot exceed a value of unity, however, since the minimum current 
would then be zero, and it would be necessary to operate on the toe of 
the characteristic curve of the vacuum tube, thus introducing unde- 
sirable distortion. We shall later find it convenient to consider the 
maximum modulation possible in a given element of the apparatus 
without introducing distortion. 

Tone Reproduction in Variable Density Records 
Let us continue to assume a source of sound producing a pressure 
variation at the microphone represented by Equation 1. Let us 
further assume the use of perfect acoustical and electrical recording 
equipment so that the current in the last stage of the recording ampli- 
fier may be represented by Equation 2. If, now, the variations in the 
exposure of the film are proportional to the variations in the current /, 
the exposure of the film may be represented by Equation 5. 

e = Eo-{-E smo)t (5) 

Here e is the value of exposure corresponding to a sound pressure p, 
Eq is the value of exposure when there is no sound before the micro- 
phone, and E is the maximum value of the sinusoidal variation of 
exposure. As before, the maximum value of e is emax'=Eo-\-E, the 
minimum value, emin = Eo~E, and the average value, eave = Eo. 
We may now proceed to find the photo-electric cell current in the 
reproducer, following very closely the graphical method devised by 
L. A. Jones. In Fig. 3, the transmission of the negative has been 
plotted on logarithmic paper as a function of the exposure. The same 
curve is obtained in this way as when density is plotted against the 
logarithm of exposure. This curve represents the characteristics of 
Eastman positive film developed to a gamma equal to unity. The value 

Rendering of Tone Values — Hardy 


of the inertia averages a little less than 0.2 candle-meter-seconds, but 
to facilitate the reading of the curves, the inertia has been assumed 
to be exactly 0.2 c.m.s. Positive film is chosen for making the negative 
because of its superior characteristics in respect to resolving power and 



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Fig. 3. Tone reproduction diagram representing ideal exposure and develop- 
ment conditions for the Variable Density type of record. 

The left half of Fig. 3 shows the characteristics of the positive 
print made from the negative shown at the right. Since the exposure 
of the positive is proportional to the transmission of the negative, 
this characteristic curve has been rotated clockwise through 90 de- 
grees. To determine the transmission of the positive corresponding 
to a given exposure in the negative, we proceed as follows: 

Starting from the point on the characteristic curve on the nega- 
tive corresponding to the exposure in question, we proceed horizontally 
to the characteristic curve of the positive and then read the resulting 
transmission of the positive. Thus, an exposure of the negative equal 
to 1.2 c.m.s. will produce a transmission of the positive equal to 0.5. 
For reasons to be discussed later, the printing light has been chosen 
so as to produce an exposure of 2.4 c.m.s. in the positive for a negative 
transmission of one. 

It is obvious that the greatest amplitude of signal is recorded 
when the modulation of the negative exposure is unity. It is also clear 
that the use of a large modulation reduces the effect of the ground 
noise. However, if the modulation of the negative exposure is made 

482 Transactions of S.M.P.E., Vol XI, No. 31, 1927 

as great as unity, it is necessary to utilize the curved portion of the 
negative characteristic curve. Thus, if the average exposure is Eq, 
the maximum exposure will be 2Eq, and the minimum exposure will be 
zero. We see from the negative characteristic curve that a minimum 
exposure less than 0.4 c.m.s. would place some part of the record on 
the toe of the curve. From the work of Hurter and Driffield, and 
others since their time, we suspect and will later show that this 
would introduce serious distortion. Let us assume a reasonable value 
of 7n for the present, say ??^ = 0.5. This will provide only half as much 
signal on the film as a modulation of one (if we could use it), but this 
deficiency may be compensated by subsequent ampHfication. To be 
sure, this will double the amplitude of the ground noise, but when 
all other conditions have been properly chosen, the ground noise is 
not a serious problem. With a modulation of 0.5, and the minimum 
exposure at 0.4 c.m.s., the average exposure must be 0.8 c.m.s. and 
the maximum exposure 1.2 c.m.s. (as indicated in Fig. 3). 

The loudness of the signal depends upon the amount of light 
reaching the photo-electric cell. Therefore the positive exposure 
should be kept as short as possible, but for the reasons mentioned 
above, the toe of the curve must not be used. Thus, the best possible 
adjustment of the printing light is that which gives an exposure of 
0.4 c.m.s. to the positive through the densest portion of the neg- 
ative. The curves in Fig. 3 have been adjusted to represent this 

By means of the above method, the reproduction of a sine wave 
has been determined for a number of cases, a few of which are rep- 
resented in Fig. 4. These curves are obtained by plotting the trans- 
mission of the positive T p as a function of the time t. Curve C 
shows the wave form resulting from the exposure and development 
conditions in Fig. 3. This curve is exactly like that of Fig. 2 and 
indicates that there has been no distortion in the photographic process. 
This result is easily predictable from previous work on the theory of 
the reproduction of tone values. It has been shown that if the product 
of the gamma of the negative and the gamma of the positive is equal 
to one, and that if all the tones of both negative and positive are 
reproduced on the straight portions of the characteristic curves, there 
will be no distortion. In other words, the transmission of the positive 
will be directly proportional to the exposure of the negative. Since the 
current in the photo-electric cell is proportional to the transmission of 
the positive, this is equivalent to the previous condition that varia- 

Rendering of Tone Values — Hardij 


tions in the current in the photo-electric cell be proportional to the 
variations in the current in the last stage of the ampHfier of the record- 
ing unit. 


V/tL ties OF T/ME 

Fig. 4. These curves sliow tlie manner in which the pure sine-wave sound of 
Fig. 2 is reproduced by the Variable Density method. Curve C is also 
a sine wave obtained by proper exposure and development of both 
negative and positive (shown in Fig. 3). Curve A represents correct 
exposure but under- development and Curve F correct exposure but over- 
development. Curves B and E show the effect of under-exposure in the 
negative, the negative being also over-developed in the latter case. Curve 
D shows the effect of over-modulation of the negative exposure. The 
seriousness of the distortion illustrated in all of these curves except C 
can be appreciated only after the listening test. 

A few other conditions of interest are also represented in Fig. 4. 
In all these curves except curve D, the modulation of the negative 
exposure has been assumed to be 0.5. Curve A represents the case 
where both negative and positive are correctly exposed; that is, 

484 Transactions of S.M.P.E., Vol XI, No. 31, 1927 

all the tones were placed on the straight portion of the characteristic 
curve, but both negative and positive were developed to a gamma of 
0.5. It will be seen that the curve is no longer symmetrical. Different 
development conditions are shown in curve F, where both negative 
and positive, although correctly exposed, were developed to a gamma 
of 2. These curves are equivalent to a fundamental sine wave of the 
same frequency as curve C plus harmonics introduced by the faulty 
development. Since the quality or timbre of a musical note depends 
on the ratios of the amplitudes of the various harmonics and funda- 
mental, this kind of distortion is evidently very serious. A skilled 
violinist is careful to bow in a manner which produces the overtones 
in the proper ratios. In fact, from a mathematical standpoint, the 
only difference between a Stradivarius and a fiddle is in the ratios of 
the overtones they will produce. We see therefore that it is important 
in variable density records to develop the negative and positive to a 
gamma-product equal to unity. 

Curve B represents the case where -both negative and positive 
were properly developed, but the negative was under-exposed, being 
given only one quarter of the amount of exposure indicated in Fig. 3. 
There is always a temptation in the case of under-exposure to remedy 
the error by increasing the extent of the development. This case is 
represented in Fig. 5, where the average negative exposure is only 
0.2 c.m.s., and both negative and positive were developed to gammas 
equal to two. The conditions represented in Fig. 5 lead to a wave 
form shown in curve E of Fig. 4. It will be seen from curves B and E 
that the general effect of under-exposure is to flatten one-half of 
the wave.^ Besides introducing harmonics, this decreases the amount 
of signal on the photo-electric cell, since the signal strength depends 
roughly on the difference between the maximum and minimum trans- 
mission of the positive. Over-development after under-exposure in an 
effort to increase the signal strength (as in curve E), simply introduces 
more distortion. The seriousness of this distortion can be appreciated 
only after a listening test. 

As stated previously, all the curves shown in Fig. 4 are plotted 
for a modulation of 0.5. In practice, this represents an upper limit 
to the modulation. By proper adjustment of the gain in the amplifier 

« This is true of both the negative and the positive. However, under-exposure 
of the positive would have flattened the other half of the wave. Since we are not 
interested in phase relations, only under-exposure in the negative has been 

tendering of Tone Values — Hardy 


preceding the recording unit, the modulation produced by the loudest 
sound can be kept below this limit. Thus, in musical terms, 50% 
modulation can be made to correspond to the entire orchestra playing 
fortissimo. As the modulation decreases, the quahty of the repro- 
duction improves; that is, errors in exposure or development of the 
negative or positive are not so serious. If it were not for the back- 

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5. Tone reproduction diagram for the conditions of exposure and devel- 
opment leading to Curve E of figure 4. 

ground of ground noise produced b}^ the graininess of the emulsion 
it would simphfy the photographic technique to use a lower modula- 
tion and to build up the signal strength in the amplifier preceding the 
loud speaker. With the emulsions which are available at present, 
however, better records are produced by adjusting the maximum mod- 
ulation to approximately 0.5 and using care in exposure and develop- 

Tone Reproduction in Variable Width Records 
Let us consider the type of record represented on the right in 
Fig. 1. When the optical system is in proper adjustment, and there is 
no sound in the microphone, one-half of the path occupied by the 
sound record will receive no exposure, while the other half will 
receive an exposure which depends on the intensity of the light, the 
speed of the film, and the dimension of the aperture in the direction 
of motion of the film. Let us assume sufficient light intensity so that 
at normal film speed this dimension of the aperture may be made 
small compared to the wave-length of sound as recorded. Assuming 

486 Transactions ofS.M.P.E., Vol. XI, No. 31, 1927 

the sound to consist of a simple low frequency sine wave as before, the 
boundary between the exposed and unexposed portion of the sound 
track is also a simple sine wave. 

Let w represent the full width of the sound track and x the 
width of the exposed portion. Let Ti represent the transmission of the 
film in the unexposed region and T2 represent the transmission in the 
exposed region. The current {i) in the photo-electric cell is then given 
by Equation 6. 

i = k[Ti{w-x)^T2x] (6) 

The constant k depends on the sensitivity of the photo-electric 

cell and the illumination of the film in the reproducer. Assuming a 

variation in sound pressure representable by Equation 1, the value 

of X with suitable electrical apparatus in proper adjustment will be 

given by Equation 7 where / is the fractional width of the track that 

is utilized. 

w wf 

x = sin CO ^ (7) 

2 2 

Substituting the value of x from Equation 7 into Equation 6, we 
obtain Equation 8. 

i=iwk(Ti-\- T2)-\-iwfKTi- T2) sin co t (8) 

This is of the same form as Equation 1 and consists of a constant 
term plus a sinusoidal variation of the same frequency as the original 
sound. It will be noticed that the amplitude of the variable term is 
proportional to the width of the sound track, the intensity of illumin- 
ation of the film in the reproducer, the sensitivity of the photo-electric 
cell, and the difference between the transparency of the exposed and 
unexposed regions {Ti — T^).'^ The maximum modulation (m) of the 
photo-electric cell current is the ratio